Electrical issue in a 1940s house

Couple of questions kind sirs ...I have no idea about electricity.

1. Mum has an electric water heater cylinder medium sized, the element (2000watt) broke and an electrician put a 3000 watt element instead of 2000 watt. It’s ok right? I was not around during the fix so I didn’t get to ask thoroughly.
2. Since mum is living alone, I wonder if it makes sense that she turns on the water heater just once every three days. She doesn’t use much water... it may reduce power costs.

I appreciate your help.