my baby is 7 months, but it's been generally the same for the last few months. she's in and out of the carrier most of the day. she often sleeps on my back, so that's 1-2 hours at a stretch. but when she wakes up she needs to pee, so she comes out to pee, and if she didn't nurse prior to her nap she'll want to nurse. then sometimes she is happy to go back in, sometimes she wants to get down and chew on a toy or crawl around for a while - especially if her brother and/or sister is interested in playing with her. it also depends on how much work i've got to do around the house and whether it's stuff i need her on my back for (like putting laundry in the washer down in the basement, or washing dishes) or whether it's something like folding clothes where she can crawl around nearby and i can keep an eye on her.
she really likes a high back carry when she is back there for long stretches, though, so she can see what i'm doing and look around more easily. sometimes i'll flip my nursing necklace around so she can play with that, too, so she's not tempted by the fragile hairs on the back of my neck.