As a relatively new DM I've adopted players rolling Investigation when attempting to loot corpses and chests, because I see other Dungeon Masters doing that as well. But since I roll for loot on certain NPCs/chests beforehand, I don't see the relevance of players always investigating for loot.
Often rolling for loot seems tedious and too time-consuming, because my players tend to want to loot each and every corpse they leave in their trail. They agree that the current looting process breaks the momentum of our encounters too much. So I'm thinking of dropping the whole 'roll for loot', unless there's specific items (such as a key) to be found or unless the player character explicitly wants to acquire information from the body. While writing this question though I realised it's unclear to me whether there's a ruling on requiring players to roll for loot.
Are there guidelines for how to speed up the looting process for a PC when attempting to loot corpses, chests, etc? Do players actually need to make a roll for loot or is this optional? I also accept answers based on successful personal experiences.