Speaking of Chester...WEEZ/WQIQ at one time had an arrangement where they were 770w by day and 1000/directional by night. Yep...they actually RAISED power at night. Don't ask me how it worked...

Nowadays, lots of AMs run with higher power at night than by day. I'd be surprised if the number of such stations in the US were smaller than 100 and I wouldn't be surprised if the number were several hundred. The first station to use higher power at night than by day may have been the AM 1330 in Youngstown OH. (I think it was WHOT at the time.) Back then, WHOT also had the distinction of having separate day and night transmitter sites, one of which had six towers; the other had five. All that for a station that ran 500W by day and 1 kW by night.
Higher power at night is now relatively common on the six graveyard channels (1230, 1240, 1340, 1400, 1450, 1490) because there are very few DAs among the Class C AMs on those frequencies and the adjacent-channel protections are more stringent by day than by night. Although the day/night power differences among the Class Cs are usually small (the cited 770W-D/1 kW-N would be fairly typical), they can be a lot more extreme among Class Bs. KFMB San Diego, for example, runs 5 kW-D/50 kW-N DA-N. Going directional by day would not allow KFMB to increase its day power. Its daytime power limitation is due to a daytimer, second-adjacent KBRT on Catalina Island.