[helene_t]

In some partnerships I play natural nonforcing jump shifts in the context of SA-like 2/1 systems. Style varies a bit between partnerhsips, but typically
1m-(pass)-2M: a weakish weak two opener, say 2-6 points
1M-(pass)-3m: just short of a GF, i.e. a broken suit with one or two outside honours, or a solid suit with nothing on the side. Shortness or maybe xx in partner's suit.

I must say that while I have good experience with 1m-2M (often leads to good contracts and the negative inference when not using them is often useful), I don't have the same good experience with 1M-3m. Often we miss a fit in hearts when opener has 5-5 in the majors, or opener misguesses when accepting the invite or not etc.

Is it a question of using the IJS more dicipled and having clearer/better agreements about them, or should we just get rid of them? Or is it likely that they actually work well and it is just my biased perception?

[Zelandakh]

IJSs are basically a system crutch to get around the fact that the F1NT response is overloaded in 2/1. I doubt many would claim this is a strong point of the system but if you don't play them, you need to find a different solution. Some alternative solutions are WJSs with a stronger range (effectively covering the 1NT-xm hand type); 2/1 GF except rebid; 1M+1 INV+ relay; and (recently posted on BBF) 2/1 nat GF or weak transfer. The trouble is that all of these have their own problems so all you are doing is moving the issue.

One thing you will find if you look back over threads on this hand type is that many BBFers prefer to GF with borderline hands rather than make the IJS. That is particularly true for responding hands that might play well in a major, which might be one way of avoiding the 5-5 issue (at the cost of reaching some thin games). Basically, when you play 2/1 you accept that you are hurting yourself on these specific hand types. It is generally regarded as a price worth paying overall but obviously there are times you will wish you had better options available.

[Jinksy]

I loathe IJSes to the extent that we've just given up on a certain subset of hands* to take them out of our system and replace them with a convention that doesn't both a) never come up and b) typically harm us when it does. This is in the context of Fantunes, where the values are shifted lower, which probably makes the sequence still less likely, but the change has been so successful that I'd need a lot of persuading to ever play them even in regular 2/1.

* We bid the suit later, after a 1N response if in the range for an IJS, and just don't ever bid it if it's weaker, unless we can do it at the two level.

[gszes]

IMHO there are better ways to use 1M 3m but if you use it in a more disciplined fashion (ie it comes up a lot less) then it can be a useful tool. Opener has AKxxx QTxx Ax xx.
Using your current parameters opener has no clue about how to proceed. Responder might have J Axx xxx AJxxxx or x xxx xxx AKQxxx. The problem is two fold for the first example. Clubs may not be the best spot (2h should be much better), but where else can opener go, and what rational reason would opener have to decide game or no game (3n) knowing that the example 1 hand types are a lot more commo9n than hand 2. Hand 2 presents opener with an easy 3n but also something more. 3c is playable so opener does not have to panic with a hand not suited for game or misfit.

That means if you limit your IJS to hand type 2 it will mostly pay off due to great accuracy though frequency will suffer as a result.

[nullve]

Zelandakh, on 2016-April-07, 08:13, said:

IJSs are basically a system crutch to get around the fact that the F1NT response is overloaded in 2/1.

A related but more fundamental reason for playing IJSs is to keep Reponder's rebid of own suit as GF, or else one can just play 2/1 GF except rebid. And this is true whether 1N is F1, SF or NF.

[fromageGB]

1m 2M certainly weak JS, but the question is really 1M 3m.

No method comes up often, but I would be reluctant to lose my 3m bids as types of major support. When you have those hands they are vital bids, but if you have the invitational minor hands then you can do other things, as suggested. My chosen option is keeping 1NT forcing, and deciding on those hands whether to GF in the minor or rebid 2NT. I think the game in a minor is probably only really viable if opener freely bids the minor himself in sequences after 1NT.

[Zelandakh]

nullve, on 2016-April-09, 08:57, said:

A related but more fundamental reason for playing IJSs is to keep Reponder's rebid of own suit as GF, or else one can just play 2/1 GF except rebid.

If you re-read my post you will see that this was covered, along with various other alternatives.