It has been a few years since I retired, but there was a big flap while still there (I think driven by federal labor laws) about docking salaried employees for time off. If a company took pay from salaried employees for being late, personal time, or leaving early; then they had to pay them for time beyond the 8 hr day - 40 hr week. Most companys concluded that it was better to not hassle the employees about the time off. If anyone abused it, they could be dealt with at review/salary adjustment time and real abusers could find that they were terminated.
I think the final policy was that if you were there at all during the day, it was a day of work and you got paid. If they officially closed the plant (VERY RARE), you got paid. If you took the whole day off, you had to take vacation if you had it. I don't remember the policy if you had no vacation left.
Regarding the earlier post about closing for 6" of snow in the Maryland area; when I was there in '63 to '65, if there was an inch of snow in the DC, VA, MD area it put the whole place into gridlock.