I keep it really simple. Until it’s boring. Then make it harder until that’s boring. Like what you are doing to start. Then maybe trot in and canter out a line. If rushing, trot in and trot out first. When that’s decent, then some simple trot in gymnastics. And for ones that are quick, a single, low jump on about a 20m circle for the canter work. Keeping them on the bend helps maintain any throughness you can achieve and helps to control the pace without getting grabby with 2 hands. Use the steering to help them relax and not rush. These days I also work a lot on the rideability and increasing the difficulty of questions asked on tiny jumps before I put the jumps higher. Maybe mix in one day occasionally higher via a simple grid (once relaxed in the small ones) to help him figure out form (or free jump if you have a good place for it) but I tend to avoid pounding the legs anymore until I get the steering and the forward and back and balance figured out over poles to Xs to 18”.
Also avoid putting the jumps up to get them to slow down / back off, which I have seen some people do. That is skipping some steps. I would rather put the jumps up when that makes the horse a little more bold / having fun compared to boring baby exercises, not because I need a bigger speed bump.