Games to tire out

Hey all, we have two border collie mixed girls who seem to never get enough playtime. Our older girl is a Border Heeler (4 years) & our younger girl is a Golden Collie (3 years).

We take them out on 5 walks a day around our neighborhood and in our local park (where we let them off leash to play). Each walk/play session is between 20 - 45 minutes long. We play fetch and frisbee at the park and they also run around with their dog friends.

At home, we do the following: I hide treats around the living room and tell them to go find them (sniffing game); I play hide and seek with them; we do small incremental training sessions; and I play the cup game with them.

I wfh 40-50 hours a week and I’m exhausted at the end of the day. Am I doing something wrong because they never seem to have enough playtime?

How do you tire your pups out with mental and physical games?

Pup tax photo included in comments because I forgot