Not HS but for youth I have been assigned the "head coach ". We get this a little too often in my opinion but it depends on how many coaches we have available. If it's not required to have both corners & I'm the only one available, I do not do normal coaching. I just tell the guys no hip toss or headlock and no stupid screwing around rock, paper, & scissors theatrics. Just after each period I speak to both quickly to keep pushing each other. The best is having 3 of us. I go by scorer's table & say nothing at all. Other 2 do limited coaching to both from each corner. I take inventory of items to address at practice & get input from both coaches in corner to add to it.