Hello, inserters can take 1 item from a line per tick (4 frames) and a conveyor can store up to 8 items. There is however a system so that if several inserters are taking from same conveyor square or if the conveyor path continue beyond that square, they will take turn so as to not starve completely any supply path. So putting more than 8 inserters to take from the end of a path cannot extract more than 8 a second (as the conveyor bring only 8 per second anyway) but could potentially take less, because some inserters will be idle some ticks, waiting for items to be shared between others. This code is not very smart to be honest, it was just an easy way to share items among several paths. Bridge work the same but can take half the content of the conveyor (so up to 4 items per ticks if the conveyor is full) this is again so that items are spread between several paths, but two bridges at the end of a conveyor line should empty it I think.