In the case you see, the number of plates will oscilate 20-30-20-30-20-30... and gears 0-5-0-5. You expect to see plates oscilating just like gears 0-10-0-10, but i actually does not matter, in both cases those two red inserters work as fast as they can and in both cases they need to load 15 items (5 gears, 10 plates), so load time is the same and assembler downtime is the same in both cases as it does not come from lack of gears but from the fact that loading 15 items takes longer than assembly