While it sounds ridiculous, there is a reasoning for this even nowadays:

Any periodic activity with a rate faster than one minute incurs the scrutiny of the Windows performance team, because periodic activity prevents the CPU from entering a low-power state. Updating the seconds in the taskbar clock is not essential to the user interface, unlike telling the user where their typing is going to go, or making sure a video plays smoothly. And the recommendation is that inessential periodic timers have a minimum period of one minute, and they should enable timer coalescing to minimize system wake-ups.

Found 1 test that seems to confirm battery life is slightly worse (2%) with seconds enabled. But this is true only when nothing is going on on screen. If you would actually work on PC, I imagine difference would be practically nonexistent.

All that said, I use seconds on my private and work PC. Was pissed when MS initially removed this as an option.