At least the model we have at our summer cottage, you can go multiple times while it's still burning since the incinerator and the part where you are doing your business are two separate areas. To "flush" you just press the button that opens the hatch and drops down in to the incinerator.

You have to empty it maybe once month and there is only handful of ash. It's definitely easier to maintain than composting toilet where usually you need to throw in some dry mulch/compost material so doesn't get smelly. Eventually you still have to empty the compost and hope it has mostly turned in to soil. It also smaller than composting toilet so you can fit in inside a small cottage.