I think it would have been easy if I'd got one who slept... As it was dc3 didn't sleep for more than 2 hours in one stretch til he was nearly 3, no matter what I did. That was very hard to juggle with school runs as he'd often only just fallen asleep when I needed to get up to take the 6 and 4 year olds. Breastfeeding was both easier because I knew what I was doing and harder because I often had to interrupt his feeds before he naturally finished because older children have an externally imposed schedule of school/ sports/ play arrangements you've set with other parents and going with the flow is harder.
Now he's older (dc3 is 7) it's easy because you're less phased by things with a 3rd child, but I sometimes wonder whether I don't parent him as well as I did the older 2 at the same ages as I have less time.
I deliberately wanted to SAH with each child til age 3 so dc3 obviously set my return to work back with all the obvious knock on effects.
Dc3 is totally different to dc1 and 2 (not due to sex as we already had one of each, just an utterly different personality) and I really thought I knew what I was doing parenting young children and dc1 and 2 were really easy, I thought 3 or 4 or 5 kids would be pretty easy. Dc3, partly but not only due to the years of not sleeping, has been quite different to parent and reminded me that what works for 1, or 2 children might not for another, at all.
The kids get on really well together and don't fight beyond a little bit of bickering. Dc3 is incredibly amusing and a really unique character, he's a wonderful little person and incredibly lovable.
I'm glad I have all 3 and families of 4 seem a bit vanilla, I like the buzz of the 3 of them in the house (or often 6+ kids as they often have friends over). It is a lot to juggle though. A 3rd isn't less of a change than a second imo, I believed that old chestnut before having dc3 but it didn't hold true for us because of sleep deprivation among other things.