Profits always drop by 3rd or 4th day, need help!

I’ve been running several campaigns, amongst those that are profitable, I’ve got some hitting 300% roi, 150% roi on a number of traffic sources.

However I realised a pattern, by the 3rd or 4th day after running, profit just tanks. Could literally drop to 10% roi or even red.

Landers don’t seem to be the problem (I think?) as its ripped as always and everyon ...