Use less nutrients and water then but the 7-10 change is spot on to avoid most problems and to provide quality nutrients just when the plants want's them. But you only need to change them IF you are following the cycle of life.

If you are just using average grow and average flower then 3 times the amount the plant uses. so 15 gallon res for a 5 gallon plant then you can change then every 2 weeks and just top off.

Personally I prefer the Cycle of life the plants are healthier and healthy is good if you want to grow larger buds.

The cycle of life does require the proper nutrients and boosters though.

The general is safer

It is up to you and your budget how you grow, but thanks for listening to the show and let me know if you have more questions, I'm happy to try to help.