@Storx: did you get any more granularity on the intervals? Seems strange you were getting best results with 3000 (that's 50 minutes without switching)...
Im sorry bud the test was spoiled by thunderstorm a few days ago, my parents house which has 2 rigs, 2 racks of 4x1080ti's per are down.. still troubleshooting the issue.. seems the motherboard is fried.. really hope that the 8 GPU's are ok...
currently im mining at 10minute intervals, because it seemed switching to often was causing a lost in profit due to switching in the middle of processing data, but going to long was pushing out off the clif of income.....
That's a damn shame, talk about luck. I hope your 1080 ti's are okay!