Those of you who have picked up a copy of my new book, Overcalling Opponent's 1NT, will undoubtedly realize that the main focus is on overcalling the opponents' 1NT openings but that I dedicate some time to discussing other uses for the theory, in other unrelated sequences. As I continue to think through permutations, new ideas come up. I thought I would share.
How about after a 1NT overcall by the opponents? Your partner, say, opens One Club, with a strong 1NT overcall. A lot of us play Lair here, where 2C is sort of a replacement for a negative double. Well, what about using the two-under approach? In the simplified version, 2C would show one or both majors with a weak hand, typically a long one-suited major (either one) or a weak hand with both majors (5-5 at least). Other calls, like 2D, 2H, and 2S, would then show the same pattern with extras. This approach would be particularly good in dealing with a R.U.N.T. 1NT overcall for those who also picked up my new book, Really Unusual Notrump (R.U.N.T.). Alternatively, a fit-showing style could be used, where 2C shows one or both majors, but if one major then with a fit for Opener's minor. Hence, for instance, after 1C, you would bid 2C with either major and clubs (or both majors).
What about tweaking Drury? After two passes, partner opens 1H. You hold 3H/4S with limit values and are concerned about missing a 4-4 spade fit. If Opener responds to your Drury call by acting as if he is responding to a one or both majors call, he bids 2D with spade preference (four spades) or 2H with heart preference (not four hearts). If he does that, then your Drury bid could be bid with a heart fit ("just hearts"), with 4S/3H ("both majors"), or with four spades and a longer minor ("just spades"). In the latter event, if partner bids 2D, you bid 2S. If he bids 2H, you also bid 2S and partner can decide what to do. You would need an unwind for when Opener has extras, of course,