I've seen a lot of problems where the input does not take into account a variable t for a number of test cases per code execution and I would like to ask why? For example today's E1 in Round 726 Div 2, why does it not for example include a t variable with the added constraint of "It is guaranteed that the sum of n,k over all test cases does not exceed 5000" or something like that? It seems like there is no advantage to not including test cases and that it only leads to weaker pre-tests.

Im talking specifically about that brief 2-3 minute window before a contest where doing anything else will cause you to get distracted or have to stop it halfway but waiting for the contest for those 2-3 minutes feels like an eternity filled with anxiousness. What do you do?