It's not about single checks,An advice we can give to beginner DM is that if you ask for a check, then a PC may fail or succeed it. So be ready to handle both success and failure. If you can’t handle both, better don’t ask a check, and decide the outcome of the action.
Setting the DC don’t matter much, choosing 5, 10, 15 or 20 and even more won’t break the game. Make a reasonable evaluation and be comfortable with your choice, but be ready for a success or a failure.
A DM who calls for DC 10 often will have PCs who succeed often and look like super heroes.
A DM who calls for DC 15 often will have PCs who fail often and look like amatuers.
A DM who calls for DC 20 often will have PCs who almost always fail and look like incompetents.
So if a DM makes a dungeon with 2 DC 15 traps, 1 DC 10 hazard, 1 DC 20 hazard, 3 DC lore checks, 1 DC 20 secret, a DC 15 Hidden door, a DC 15 obstacle.... the party of 4 will look like bumbling goofs.