Crate Advice! Leaving puppy in kitchen with crate door off?

I have a 12 week old puppy who is very accustomed to her crate. I am still a bit weary about leaving her in there for long periods of time because she is still not on a regular poop schedule and I am worried about her being able to hold it when I am gone. I live in an apartment and have her going potty on a gr mat which she does great. If I have to leave her for more than 2 hours, and I am not sure if she needs to poop still, is it better to keep her in the kitchen blocked off with her crate in there with the door off and her potty mat in the kitchen also? Or is that defeating the crate training purpose?