[jillybean]

2♣:2♦
2♠:2N

2♣ gf, 2♦ waiting (2♥ bust)

Is your 2♠ bid typically 5 or 6 and what sort of hand will 2N show?

[Mbodell]

2♠ is an unbalanced hand or semi-balanced hand with 5+ spades. 6 will be quite frequent, but 55 or a strong 5431 is certainly possible.

2NT to me suggests a quite good hand with no fit. Quite good because it is stealing nt and usually I'd just bid my suit (even 4 card ones if 1444 or 2(344)) at the 3-level if I wasn't going to support spades.

[jillybean]

Will partner routinely support openers 2M bid with 2 card support? (2344)

[mike777]

2d is art. and gf promising any random a or k.

2s is natural 5 card suit or more, 4 loser hand.

2nt is just some bal hand with at least a k and denies 3s. I wont bid a 4 card suit over 2s and try to avoid weak 5 card minor suits. I do not worry about the weaker hand playing nt.

[Stephen Tu]

2S only promises 5 so responder shouldn't routinely support on 2 cards. It's probably more often 6+ than 5, (more hands with 6+ suits qualify as within a trick of game, also people are more conservative opening 2c with 2-suiters), but even so for close slam decisions there is big difference between 8 cd fit vs. 9 cd fit, or 9 cd fit vs. 10 cd fit; knowledge of a 3rd card is valuable even when opener has 6+.

I also wouldn't worry about declaring NT with the weak hand. Reasonably often:
-opener has solid 6+ suit, insists on major anyway
-it was responder's honor(s) that needed protection from the lead
-opener's side suit stopper wasn't broken (AK, A, KQ alone) and it didn't matter significantly
- partner's stopper is the ace and you have 9 tricks off the top
- opp's honors were onside and it didn't matter.
- they lead wrong suit
- if opener had a semi-bal hand with lots of tenaces to protect arguably he could have chosen to rebid 2nt

I think bidding 4 cd suits as MBodell suggests will hurt you in finding alternative strains more than any occasional wrong-sided 3nt.