I have found pure stacked work great where it is blended or there is a crown.
Especially the 3 3/8 stacked. Covers a lot of boards, starts in the heads, the ball must almost always be swung. Hooks all the way down the lane, or attempts to hook, heads, mids and backend.
All stacked will try to get up high on the head pin, in relation to most other drills. If you start to see 4 pins, (or for lefty 6 pins) and you can't adjust off them, or pocket splits ready to happen, it is often times to switch to drills that do not maximize the core potential(the stacked drilling).
Kicked out cgs will increase midlane and decrease pure backend angle Hook set.
Kicked under grip cgs will decrease midlande and decrease backend angle from inside.
Many bowlers can not see the pins starting to fall slowly. Fortunately at times I've been able to see it and switched to the less entry angle drillings above and been able to put a little cash in my pocket here and there.
On the other spectrum if the ball can't get high enough on the head pin it is often a great time to think about the stacked drilling.
REgards,
Luckylefty
PS I find all stacked drillings have the same flight charecteristics.
Whether 3 3/8, 4 X 4, 5 1/2 X 5 1/2, the ball must be swung a little in the heads and midlane. The difference is only in the amount of total flair or boards covered! 3 3/8 the most, 5 1/2 the least.