pBH farm vs pBH tournaments?

hey all, I more or less just finished pBH for farming and went to the calculator to figure out what has to happen to get it for tournies. I had incorrectly assumed that I would need to make up for the 12 seconds the perk gives me for it to happen in tournies.

However reducing the cooldown by 10 and putting 2 more pts into duration. Only shows an uptime of 96%

What happens I tournies that I'm missing that's losing me that extra 4%? I also would assume waves moving faster (or at least it seems like they do) in tournaments would result in more packages making it easier.

This is in plat and low Champs BTW if that matters. Thanks all!