[Oldtimer]

i just did 11 splits and will be happy if 6 are mated and laying on july 15th when i check again.

6 out of the 11 splits worked; one of the 11 splits queen never hatched.

Sounds like you were on the money.

Looking at your setup, you say the hives entrances are alternated, that will work quite well because there will be a middle and an edge nuc pointing each direction, and the queens will be able to tell the difference.
Like some other posters have said, color is harder to prove definate results. But hey, it can't hurt. I did not have time to do elaborate colur schemes, but bees can recognise patterns, so what i sometimes did just with a slash of the paintbrush, would do a line going right to the entrance, then another nuc there would be a 1/2 circle around the entrance, then some other pattern on another nuc, and so on. Did it work? I really never had strong evidence that it did, but it was quick to do and didn't hurt any.