What do people think of on knee push-ups when if are they appropriate

Knee push-ups are fine. Inclines are also good.

Another option that I use for someone who is in between the ability to do a full push-up and a knee push-up is to do the eccentric phase (the “down”) from a full push-up position, drop their knees, then do the concentric phase (the “up”) from the knees. Since we’re typically stronger eccentrically than concentrically, it’s a small progression to help someone move beyond doing knee push-ups forever.