How much crate time is too much?

Hi everybody! I have two small, but grown, mutts. One is a Jack Russell mix, the other is a Schnauzer mix.

They are very sweet, and mostly well behaved dogs. I live in an apartment, and I feel very bad that I crate them from 8-5 daily while I'm at work, and at bedtime too.

I try to give them lots of exercise before and after work. But I still feel like the amount of time they spend in their crates is cruel...

Has anyone else been in this situation? Doggie daycare and petsitters/dogwalkers are out of my budget where I live. Am I being cruel to my dogs?

Thanks for your input. I feel like a bad pet parent.