Hi,
I said it would freeze the experiment “if you don’t have enough items with each label to consistently break series of N items sharing the same label.” If your ratio is 1 experimental item for 2 fillers, the only constraint you have is you cannot go lower than series of 2 same-labeled trials, because then you would be forcing each filler to always be followed by at least one experimental item, but you would run out of experimental items after separating the first half of your filler items. Allowing series of 2 is fine though, because then you have enough items with both labels
Jeremy