Hello, With no booster, basically it’s all about how many gallons are used and if those gallons are all given the same temperature rise. If so, the draw rate doesn’t matter much.
One more thought however is what big draws do to your heater. If the heater gets fully drained of hot water, the cold fill water can cause condensation in the flue, which can shorten the life of the heater. So, for fun, watch the burner after a heavy use and see if you’re getting lots of condensation dripping into the combustion chamber. If so, spreading out the use could help your heater to live longer. 😉