bluecalm, on 2011-March-27, 15:40, said:
It's MP's and I am asking about general principle more than actual hand.
OK, general principles.
When dummy has nothing you need take into account, I think attitude is more important than length. I would lead high indicating that I have no desire for partner to lead away from any split holding he has. A low card indicates that I will be happy to have that suit returned (eg have trick-taking honour).
When dummy has values and I have declared no more tick-taking potential in that suit (eg dummy started with Qxx and I win with the A from A953, then I show length (normal) by leading back the 3.
I don't know if this is standard, but I'm sure it is common.