You are right, they would probably have highs and lows. However, this also happens to some extent with seed mixes- one day's bowl might contain more high protein ingredients, the next days, not as much. Or if you fill the bowl once every few days, the first day your hamster may eat all the tastiest, probably high protein bits, and the next few days have to eat the lower protein parts.
This is probably exactly why I leave food in until it's gone. I just felt like changing their food everyday at the same time regardless of how much they have eaten is not only a waste of money, but it also allows the hamster to only pick at what they enjoy most. And I am a strong advocate for tough love, LOL!