Bounced around a bit, so I'll break it up.

Jow Ga:
We did a lot of pad & bag work in class anyway.
We spent a lot of time with push kicks (thrusting through the heel vs using the ball like muay thai), as well as sidekicks & round kicks.

We did a fair amount of partner work for throws & kick catches leading to throws.

I used to do a lot of gwa-sow-charp on the bag; I'll still break it out occasionally.
There are a couple of other jow ga combos I used to do as well:
gwa-pow-charp
double kup

Also in Jow Ga there are a few combos in the forms that are basically just flashy versions of basic stuff:
grab with lead, punch with rear
sidestep/angle, parry with lead, punch with rear

*I think Jow Ga actually switches the terminology, so I'm going with the more common terminology:
gwa = backfist - either falling, rising, or horizontal
sow = overhand/haymaker
charp = lead straight that you really sit on
pow = upper cut
kup = hook

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Mantis

When I did it, we only hit stuff on Saturdays. That was also our sparring day.
We did a lot of low round kick, mid round kicks, push kicks, side kicks.
Remember doing a lot of Ng-Lo-Choy (hook, grab, punch) and even a bit of overhands (thought it was fan che, but might've also been sow choy).
We did a lot of breakfalls at one point, which i continued at a shuai chiao school.

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Xingyi

I've done the 5 elements on the bags & with partners.
Didn't string them together as much as Maverick described.
We did a good amount of twisting push kick.
I used this stuff in sparring much later on in san shou.

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Taiji

When I trained we did a lot of form, a bit of partner work, and free-form push hands.
Later on, in san shou, we picked out a lot of the throws as counters to attacks - like the wave hands through clouds kick catch, snake creeps down fireman's carry, and some push kick scoops. Brush knee push can also break down to a simple lead parry - rear punch counter.
Still use a lot of it.