Yeah, I have trouble telling from the video as well. I cannot exclude that the pressure was never high, and I cannot exclude that the pressure was high at times or a lot of the time. I don't recall whether I saw Chauvin seemingly shift back and forth. The height difference between Floyd's back and his neck might have made it possibly more severe, possibly less severe. It might have made it more difficult for Chauvin to balance, and thus end up applying more pressure at times. Chauvin also had his hands in his pockets as I recall, at least a lot of the time, which I would guess would make balancing more difficult.

It still seems incredibly strange to me that he didn't move the pin from Floyd's neck to his back after Floyd stopped moving or talking. Why not check whether he is conscious? Whether he is breathing? A large number of other things? Especially given Floyd's previous repeated talking of "I can't breath" and them talking about him possibly being sick or drugged up or similar. And... the neck is an obvious fragile and vulnerable part...