Empty Triangles Are NOT Bad Shape Per Se

I'm getting more and more irritated whenever I see people criticise empty triangles wrongly. Yes, in general they are bad shape, but there are important exceptions. They have their uses for example here:



This is from a review on GTL and the reviewer (1kyu) said "The empty triangle. You should be attacking, but instead he forces you into bad shape." Well, whether this is an attacking or defending move is by the by, but what it definitely is not is bad shape. The rule of thumb that determines this is that the triangle is facing inwards into white's own territory. OK, you might think, what is a 7 kyu player doing criticising a 1 kyu player. Well, this comes from a 4 dan player and I've confirmed it with a 5 dan pro! This position illustrates this principle very well. White is now 110% alive, wheras pushing along with black's hane would introduce a cutting point (and there's a nasty variation for black here if white doesn't cover it which takes away white's outer eye, which could reduce the group to one eye). White's shape is perfect here! He makes one move, is alive and it's sente as it activates the cut through black's hane (which would be a very severe cut!).

Here are some other examples that I can think of where making empty trianles can be ok:

a) Making nakade shapes.
b) Making super sente moves (like preparing severe cuts etc).
c) Making eyes (this is covered by the rule of thumb above), but is a special case.
d) Making seki.
e) Semeai when it's the "only move to make".
f) Part of some really evil tesuji.

There are probably other reasons. Watch ehough pro games and you will see plenty of empty triangles!