It's not "too much". It's one more thing to track, when we are already tracking HP, positioning, initiative, actions, advantage/disadvantage, and any number of situational modifiers. Every additional thing you need to track increases the odds that you will somehow screw up something else.
Worse, it is very hard to justify the value of tracking this. Are most 1-minute spells so powerful that adding an extra round or two to the duration, once in every dozen combats, will be completely unbalancing? Is the game so simplistic that adding one more countdown is the only way to make it interesting? Do one minute durations add verisimilitude because it's impossible to accept magic that doesn't jive with modern timekeeping techniques?
Then have the caster track it. There's no reason a player can't declare number of rounds remaining on his or her spell/potion/item effect.
The value of that extra round or two depends on what's occuring in that extra round or two. Would you accept "But it's the last round of the fight - ignore the 10 damage that put me under zero hp!"
That extra round or two has the potential to drastically change the outcome of an encounter, an entire adventure, conceivably an entire campaign depending on what occurs. I'm not playing D&D to handwave the players to inevitable success.
The devil is in the details, and spell durations are one of those details.