[dwar0123]

Edit: I was mistaken, no sense wasting your time with the original post

[Stephen Tu]

You need to finish Kantar's defense book .

Pretty sure he should cover that leading low from 3 to an honor is std, even in partner's suit. It does lead to a bit of a guess in positions like these (although given bidding declarer more likely to be stiff), but overall it saves tricks, because if you are unsure whether partner holds the T9, you are just blowing possible tricks when suits are more like say
Jxx Kx AQ9xx Txx
or
Jxx qx AKxxx Txx
or
Jxx xx Kxxxx AQT
around the table. Leading low, declarer has to ruff the third round, or somehow get rid of it. Leading high, declarer's third round card is a winner, and might create a useful discard elsewhere. Basically there is reasonable possibility of having to keep an honor over what declarer has.

"Lead high in partner's suit" is a misconception a lot of beginning players pick up. Lead high from sequences, or doubletons, but from 3 to a (non-ace) honor leading low is going to work out better in the long run. You can lead high from nothing if you've raised in the auction and partner won't play you for a doubleton. You can also bang down bare aces if alternatives look worse; underleading aces vs. suit contracts obviously should be avoided also.

There are some exceptions if you *KNOW* declarer is short in the suit from the auction, or vs. some high level contracts where partner has a ton of cards in the suit and you think you might need to retain the lead, and that you are probably getting 1 trick max in the suit.

[dwar0123]

You are of course correct, I misremembered what I had read and while this is a great way to reinforce the lesson it is still a little embarrassing.

Oh well.