No it's 15 seconds, because first 5 sec = 1 proc and 2nd proc = 10 sec = total of 15 sec
It doesn't make sense, it procced probably instantly, lucky/unlucky
that "6th/7th" proc is when the PPM reset, aka it was his 2nd proc out of his 5
It should be really easy to find warlocks getting 6+ procs in 5.4.8 if it's true, but I showed 7 games from start to finish where he only gets max 5, even games where ppl only get 4 procs as well.
just find a game like late s15 of a start to finish match (like when u see the match starts until he gets first nightfall proc then wait 1 min)