Tick, I never hesitate to set them close together.Sometimes only a couple feet apart.I have had doubles,triples ,quadruples and even 8 at one time.
The 8 out of 8 330s were all set in less than 100 feet.
I do alternate lures at my sets--Moundmaster #1 at the first,Moundmaster #2 at the second---back to Moundmater#1 at the third and alternate right down the line.
The picture of the 8 beaver graced the cover of the Fur Taker Magazine,about a year and a half ago.
Tom