My brother turned 3 yr old four days after my birth. My sister was 22 months at the time. My Mum was only 20 yrs old at the time.
I don't know how it was for my parents....but as the kid, I enjoyed the close age gap. I not only had siblings, but I had peers growing up.
And as a kid, my Mum felt it was easier having us close in age. She only ever had to sit through 2 events for the kids. Like when we played baseball. My sister and I were in the same age group and my brother was in the higher age group. For other activities my sister and brother were together and I was in the younger group.
Also, hand me downs were easier. Clothes and stuff just went from one kid directly to another. There was no guessing about should I keep it or not and having to store them somewhere. Clothes were just used until all kids grew out of them or wore them out.
Also, less toys needed. No need for big kid toys AND toddler toys AND baby toys all over the house. We had a bunch of toys that we all played with and then a few toys that were just ours.
And when I was old enough to go to sleep over camp my Mum was able to send all of us and have a week break to herself each summer.
No need for her to be stuck with one mopey kid being left out of the fun the older siblings were having.
One draw back was that my sister was still in diapers when I was born. And my brother decided he wanted to wear diapers again too. So for a while, she had 3 kids in diapers. He quickly went back to being potty trained.