Just wondering. Obviously control decks would be laden, but I'm wondering about aggro and midrange decks.

The aggro decks in Standard run like 4-6 interactive spells (e.g. Craig Wescoe's article: http://magic.tcgplayer.com/db/article.a ... =4-28-2017) and I completely don't understand how he can get away with so few spells since it means he may not be able to e.g. kill a Winding Constrictor or other important creature. A creature big enough he cannot attack into is also "the end".

On the other hand running too many interactive spells is clearly bad when you need threats, or when you run into a control deck.

How many interactive spells is a good number?

4-6 in pure linear Aggro
6-9 in lower midrange Aggro
9-12 w/ sweepers in pure midrange (possibly a few more)

Or at least that's how I usually build.

All the things in control.

Also, a lot of this can be adjusted based on draw in the deck.

edit: don't get too confused by what the pro-players do with access to sideboards though. That first game, he expects to win... then he will sideboard in hate - possibly lots of it - to try to snatch the next game from the opponent which will probably side in sweepers/etc... This mentality is not repeatable in Duels - because you don't get to play a second match. (even with all of that said, these decks are odd, because they a pure aggro, with no red, which usually has a bunch of spells which double as removal and direct damage. Also, I have no faith that these decks would do well right now in Standard competitive play - but that's a totally different issue).

(also most of our aggro decks are lower midrange, because our 1 drops are comparative crap. Meaning we aren't fast enough to just ignore the need for removal, like they can)

You can't give a set number. You have to factor in the composition of the meta, the speed, reach and curve of your deck. Other non spell based interaction e.g. planeswalkers. I piloted Jund Monsters through Theros block and main decked 7, but if I was playing midrange in current standard I'd look at 8 or 9.

For Duels I think 8-9 is also a good number, but again it's what fits the deck. I'm running a midrange variant of Mardu Vehicles running 3 Push 3 Unlicensed and 2 Harnessed and that works nicely.

Yeah, That's my usual breakdown too, except I run 3/3/3.

Depends on the midrange/aggro deck I'm building and the state of the meta. For example, I might run 6-8 in my current midrange/aggro builds.

for aggro I tend to take shock/harnessed lightning.
normally if i'm playing red/x, shock because it has the option to go to the dome and at worst is killing a creature.
lightning because it synergizes with other energy cards and kills most things when paired with aether hub.
Does the red cartouche count as interaction in aggro? lol.

You don't understand why a White Weenie deck is uninterested in interactive spells?

I don't understand the same way I don't understand how I could've written "I completely don't understand" and you are still capable of asking this question. Do you not understand English?

Do you find that with this kind of split you can easily be stonewalled, e.g. if opponent plays a 5/5 Woodland Wanderer or a Kalitas threatening to untap with a hand full of removal and you haven't drawn Unlicensed Disintegration? Or do you just husband your premium removal like crazy and do not use them if you don't have to just to answer cards like these? Even though that would mean giving up attack steps while holding the removal spell?

4-6 interactive spells in pure linear aggro is daring too in my experience, e.g. you go first with the mono white weenie deck in the OP and game plays out like this:

T1:
You: Land, Expedition Envoy, go.
Opponent: Land, go.

T2:
You: Land, Town Gossipmonger, Thraben Inspector, attack for 2, go.
Opponent: Land, go.

T3:
You: Land, Always Watching, attack for 7, go.
Opponent: Land, Thalia, Heretic Cathar, go.

T4:
You: Can't attack ...
Opponent: Land, Gideon AoZ, go.

Either way sounds like dangerous business, even on the play against an opponent that didn't interact on turns one and two.

Aggro is dangerous business. That's kind of the fun of it. Win big, or lose fast.

Got to aggree with that. Its kill your opponent or die trying, that's why I like aggro so much.
Btw, my Rakdicide deck is the embodiment of this philosophy, I've got to post the current build soon, its so much fun.

Yeah! Get to work. !

I'm super surprised he's using Gust Walker btw, now I have to try it out.

You don't always lose fast with aggro, believe me

You should rephrase to "win fast or concede fast"

Here you go:
viewtopic.php?f=61&t=18694#p559250

Vert has a bad habit of assuming people have a deeper understanding of things than they actually do.

To better answer your question, most aggro decks try to run relatively light on board interaction for a number of reasons. One of which is often that in an aggro shell we are more concerned with our own board than we are our opponents. The majority of aggro decks are either going to be packing a good deal of evasion creatures, or are going to be running enough cheap threats that they can flood the board and go wider than their opponent.

As such, we ideally don't need to be running a lot of board interaction and can instead devote those slots to running more threats, since in most cases playing aggro means racing, either racing your opponents creatures (in an aggro vs aggro or midrange matchup) or racing against your opponent stabilizing (in an aggro vs control or combo matchup). Running relatively light on removal generally tends to help with both of these scenarios, since in the aggro vs aggro/midrange matchup the abundance of threats help up race the opponents creatures, and in the aggro vs control/combo matchup the abundance of threats help us to overcome the fact that we have to deal with an abundance of removal.

Of course we still want to be running some removal, as it can and does help with racing the opponent in certain scenarios (like removing blockers to push damage or removing a creature to tempo an opponent), and there are times when we just have to answer a threat or we lose. We generally don't want to be running too much though as regardless of the matchup getting opening hands full of removal instead of threats is generally bad for us, and drawing into a bunch of removal when you need threats to close out a game can be equally bad.

The (somewhat) exception to this rule is removal that also functions as reach (read:burn) which aggro decks can generally afford to run a little heavier on than strict removal since it can serve the purpose of removal but can also be used to speed up or finish out the race more so than traditional removal. We still don't want to be running too much of that though (unless we are going full on burn, which isn't really aggro) since again getting an opening hand full of Shocks and the like isn't likely to get the job done.

Makes a lot of sense, I always go too heavy on removal when I build for creature based aggro as I usually run mid-range and control. I find it hard to not to build defensively even for an aggressive deck!

Also, Standard doesn't have a free mulligan, so they need a higher threat density because throwing back hands immediately starts hurting.