I have always felt that despite having above average strength, I have a hard time staying in a strong position as I come to release. As such, I want to start experimenting with some different pitches (I drill my own stuff these days). Obviously, I know that thumb/joint flexibility is a major part of determining appropriate pitches for each bowler. Still, I was curious as to what types of pitch orientations tend to promote a good, crisp, clean, and powerful release. What have you guys and gals tried, and how has it worked out for you or the bowlers you drill for?

I started drilling my own stuff to figure out what I really need. Have done a lot of experimentation.

Could check out tri-grip or slowinki's ADT - both are similar and in practical terms add left pitch (or right pitch for a lefty). What these also do is probably give better pitches in finger holes which helps a lot.

I break it down this way:
Things that will increase the ball's hold on hand and decrease grip pressure:
- Forward pitch
- Sharper bevel (weird or excessive bevels can be a hidden cause of poor grip - I suggest keep it sharp and then slowly smooth with sandpaper or bevel knife as needed)
- Longer span (until point it is too long - then get pain and ball drops out)
- Tighter thumb hole (adds more squeeze than ball locking onto thumb)

The difficulty it can be hard to identity where problem is and try to correct one thing, by messing up another. For example, a short span can be compensated for, by trying to use super sharp bevel, or adding excessive forward pitch. Of if span is a bit too long, then maybe someone tries to fix that by adding some reverse pitch.

I have tried dozens of configurations with ball drillers and myself to find something as perfect as possible. I don't think there is a secret formula, but being aware of all the variables is important. Recently I realized that my span was way too short (years ago it was too long) and that I had been correcting the short span with lots of forward pitch (for a long time used 7/16 - whereas 1/4 is more reasonable).

Finally, there is a lot that can be done with tape to shape the thumb hole besides adding in and out to front. I use round hole's, slightly oval with sand paper, then use tape to oval more.

All the factors turn into a bit of a balancing act.

Yeah, I wasn't really looking for a magical answer here. I know that there is no perfect set of pitches that work for every bowler. I was just more interested to hear what others have tried and how it worked out. In the end, for me, it's just going to come down to experimentation.

Haha.. yep.. I'm the weirdo with the 3/4 right in the thumb. I agree with everything on here.  ITZPS is right on about getting  your thumb right above the hole.   From my experience, first get your span right.  After you know the span is good, the easiest way to tell if your thumb pitches are correct is to drill a snug thumb with no bevel.  If you can't get out then you need to adjust your thumb pitch. Most drillers use bevel to fix an incorrect pitch.  Before I adjusted my thumb pitch I would need a ton of bevel to clear the hole.  Now I barely need any and what I do have is just for comfort.