Team Effort
I pity the poor slaves building a pyramid while using the 5e rules, as”help” just increases their odds of success but doesn’t increase their maximum limits. They’re just as effective as slaves working alone that’re rolling hot.
I won’t miss the chorus of “I assist” and compiling of bonuses when a character is attempting a mundane task. Because there’s no penalty to failing to assist, everyone tries to help out, stacking circumstance bonuses onto the check. It’s a little silly trying and “assist” someone in picking a lock, recalling lore on demons, or hiding beneath some underbrush. What exactly are they doing when helping with an Intelligence check: shouting out random facts or trivia?
But sometimes assistance from multiple people should work. Physical tasks are the most obvious, such as lifting or dragging a heavy object.
As for many other things in this kind of games, I’d say that logic and judgment are what’s needed from the DM, rather than a completely detailed set of rules. Nonetheless, while in 3.5 it was clearly specified that there were some tasks that couldn’t receive assistance, and others that could benefit from just one or two helpers, in 5th edition there’s no such a thing. A pity, since it is really detailed on backgrounds; it wouldn’t have been so hard to state something specific in the ability descriptions, especially since they reduced their numbers to a more acceptable one than in 3.5.