"Is it bad to wear foundation every day?"
This all depends on your skin & how it reacts to wearing make up, but no, it's perfectly okay to wear foundation as often as you like!
It's always nice to give your skin a little break from make up to just let it be, but you can do this at night time when you're sleeping!
Just make sure you take off your make up before going to bed & moisturize your skin to keep it feeling soft & fresh!
In saying that, if your having problems with your skin & it seems to get worse when wearing make up, you may want to check it's not your foundation causing the issues.
I only recommend make up that I have never had any issues with sensitivity when using.
Everyone is different though, so it's absolutely worth making sure it's not a product you're using on an every day basis that's causing the issue!