It can be an issue if the game can do complex actions at any time: if you then need to do all of it in one gigantic update after e.g. 24 hours of being in the background, it may take too long to compute that one long tick. Depending on what type of game it is. If it just has to compute "so many resources per second produced" it's easy of course and you can use the delta between last tick (if Date.now() works correctly), but if the game can auto-build various things with complex interactions, it can become computationally complex if it has to do all at once.