One leg, all the work. Find and fix your weak side.
Keep both hips level the whole rep, don't let the free-leg side dip down.
Bridging on one leg forces a single glute to handle the full job of extending your hip, with no stronger side sneaking in to help. The hamstrings assist from the bent-knee position to drive your heel into the floor, while keeping the pelvis level turns every rep into a stability test. It earns its place as a screen and a fix for left-right imbalances, and as a low-cost glute builder you can do anywhere.
The glute on your working side is not controlling the pelvis yet. Slow the rep down, push hard through the planted heel, and stop the set the moment you cannot keep both hip bones level.
Much harder per rep. One glute takes all the load and also has to stop your pelvis rotating, so expect roughly half the reps you would get on two legs.
Add a pause at the top, slow the lowering phase, or elevate your planted foot on a step for more range. Once those feel easy, adding load or moving to hip thrusts is the natural next step.
