How do good partnerships adjust their systems when overcalling, instead of opening, 1NT?

Question

Over an opening bid of 1NT, responders will use a variety of systems, such as Stayman, (Jacoby) transfers,etc.

But suppose the sequence was South: 1 diamond, West 1NT, North, Pass, and you are East. You are confronted with the fact that you are dealing with an overcall, and South's one diamond bid means that if you bid 2 clubs (and partner responds two diamonds), or you bid two diamonds yourself, you are bidding the opponents' suit.

Do good partnerships persist with "systems on," or would they revert to natural bidding, or is it "some of each"? What are the advantages and disadvantages of "systems on" versus "systems off"?

Answer 1

In my experience, most partnerships simply play System On. The intent and extent of inquiry is not, for the most part, affected by the existence of a prior opening call. This makes the benefit of a modified system fairly small, particularly compared to the memory and discussion cost of an alternate system.

For more rigorous partnerships, perhaps a transfer into Opener's (major) suit may be a specialized asking bid; but I see no benefit to doing the same in a minor suit that is frequently only 3-cards long.

It's been a very long time since I played regularly against truly top-notch opponents; so as to what those top-tier experts are currently doing here I will not speculate.