If a lock has cumulative chances set as true, then chances can be accumulated while you’re away from the app. If for example you have to draw each hour and was away from the app for 4 hours you would have 4 chances when you return. With a non-cumulative lock you would only have 1 chance.
Cumulative locks also count chances based on the time locked, and not when you last picked a card. For example, if you start the lock at 1PM with hourly draws, take your first pick and then come back at 2:30PM for your next pick, you would have 1 chance, and only 30 minutes left until your next pick.
That same example on a non-cumulative lock would start the hour countdown from the time you picked the card i.e. 2:30PM, so after picking a card at 2:30PM you wouldn’t be able to pick again until 3:30PM.
With a non-cumulative lock, the total time locked can be a lot longer if you’re not picking cards regularly and on time.