Here's a car analogy: Most people want a smooth ride when they drive a car. If you accelerate progressively, you'll stay comfortably in your seat. Slam on the brakes and you'll get tossed forward. Slam on the gas and you'll get crushed against the seat.
In chop, the piles of snow can create a braking effect. When you encounter a pile, it's important to keep the feet moving forward in order to break through the resistance. This is only possible if you have mobility in the lower joints. So instead of keeping the shins against the tongue, which will put you in a static position and often toss you over the handlebars, I'd suggest keeping the feet moving forward. Chop is a situation where constant movement is necessary because the piles can change so frequently. An exercises like shuffling the feet forward/backward is a great way to activate the lower joints. On more consistent conditions (where the snow is flattened), you could work on hockey stops or pivot slips to activate some mobility laterally as well. Chop is also a time where it's OK to accept that your turns won't be perfect! Chop gives you feedback on your balance and mobility, so take advantage when you can.
I also ski chop with more tipping rather than twisting movements; twisting is just less effective (or ineffective depending on the chop density and your skis). For me to make turns in chop, I really need to balance over the outside ski, and let my mass move towards the outside of the arc, in order to use the ski design. Any rushing movement results in falling to the inside of the arc, which causes a loss of pressure on the outside ski, and a loss of turn shape, and a loss of speed control, and a loss of setup for the next turn. (To be honest, this is also how I aim to ski on groomers; the only real difference is that I might need to use more fore-aft movement on chop, and my balance can be a bit more two-footed in chop at the apex.) Yes, you will move a lot faster than when twisting
