[jillybean]

15-17nt

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[mike777]

would rebid 1NT

1d-1s-1nt

[apollo1201]

With this near solid D suit, you have to pick the least lie. Rebidding them is terrifying.

So either it is 1D 1S 1NT and partner might end up in a 5-1 fit. But finding H will be much easier. Or sometimes partner passes and the spot is not so bad.

Or it is 1D 1S 2C and see from there (maybe you end in a better fit). But we are virtually losing H.

The risk is with a weak hand opposite. With a string partner we will reach the appropriate game.

Some players play 1m 2H to show a weakish 5S and 4+H to ease finding M contacts and avoid some tricky rebids by opener. It eases some sequences with a fit and find good games with little HCP but sometimes you end up in a bad 2M instead of a better 2m, or 3m-1 vs 2m making. Consequences on other sequences (1m 2H strong, NMF, etc.) are also to be considered.

[awm]

You say "plan your rebid" but you never said what partner's response is. In particular:

1. If partner responds 1♥, this is something of a 2.5♥ rebid. Is anyone up for the 3♥ raise?
2. If partner responds 1NT, you know the opponents have a 9+ card spade fit. Pass and hope they don't find it? Or rebid 2♣/2♦?
3. If partner responds 2♣, many people play that 2♦ by opener promises five. Does this suit count as a five-carder? Or raise clubs? Or 2♥ (presuming that doesn't show extras in this auction)?

Of course, it is also possible that the opponents are in the bidding, and you need to make some rebid decisions there too.

People seem to fixate so much on this "what if partner bids my singleton" that they don't always consider all the many other ways the auction can continue.