Is one washing machine per household a fair rule for a building with three shared machines?

I went downstairs with one basket and found all three washing machines running. The resident using them said, "I have six loads. Doing them one at a time would take my whole Sunday." She has a large household and says Sunday morning is when she can manage the laundry.

It's also the only window I have before my weekend shift. Each machine costs $2 per cycle. There are no advance bookings and no posted limit on how many a household can use at once. I waited through the first cycles, but she had the next loads ready before I reached an empty machine.

I suggested that management consider a one-machine-per-household rule when someone is waiting. She said that would make the shared room much less useful for families. I can see that three machines standing empty on a weekday aren't much help to her if she can't be there then.

What would be a fair proposal to put to the manager? I want a turn in the time available to me, without treating a household with more laundry as though it is doing something wrong by needing more cycles.