The top of the ROM (range of motion) for hip thrusts is the hardest portion, and lifters usually skimp on this when they rep out to failure. The hips rise lower and lower on each rep. Combat this tendency by performing a 10-second iso hold on the last rep of each set.
This keeps your form solid as you gain strength. It also induces a killer glute burn. At around 6-8 seconds into the hold, you'll notice that your hips will want to drop. When this happens, push the hips upward by squeezing the glutes, making sure that the last few seconds of the iso hold are maximally effective.
Hip Thrust, 675 Pounds
Even when performing a 1RM or heavy single, attempt to hold the top position for several seconds.