Have you drained the tank? My 50gal tank was out of hot water in about 20m due to excessive buildup of sediment in the tank. Upgraded to 80gal hybrid and I can take an hour long shower now without having to turn the handle to compensate for lower water temp.

Kids took a bath in our 50gal jacuzzi tub, then they took a 20m shower, then the wife and I took a shower after and we just started to run out of water after 20mins.

80gar hybrid Rheem. Heating water after running out takes 4hours(we're asleep anyway) and only costs 20-30¢