Ah yer, this interests me. Its down to the cross overs of each loop or midi part. I think when your working with 3/16ths it crosses over on the 12th bar. 3 + 3 + 3 + 3 =12 (as oposed to the standard 17). Otherwise when another sound comes in it doesnt sound on the one. Try creating parts and then copy them across the arrangment and see where they cross over. I havnt yet tried this but i would imagine it gets complicated?!?

Anyone else know much about this?