Yes - you are free to work a high number of hours one week and to work very few or no hours another week, based on your personal commitments or your financial objectives.
Important: if you are working without a Minimum Guarantee slot, you can just go online and do some deliveries, and go back offline as you please. You will then be paid per delivery and any delivery rewards.
If you are working on-slot however, you will need to follow these guidelines to be eligible for Minimum Guarantee (MG). You would then receive MG and rewards.