Crib mattress help!?

So I've been seeing a lot of cribs with the mattress down really low. Is that the norm? I have mine at the highest mostly because I'm super short. But also since baby doesn't move much it'll be easier to get her out. But should I not do this?  With my son he has a bassinet right by my bedside and once he got a little bigger I put him in the crib, of course lowered so he couldn't escape! But should I do this from day 1?