We have 5. The elder 4 were born within 5.5 years, and the youngest came along 15 years later. We are done
.
Going from 3-4 was hard. In terms of looking after them he slotted in with the others, but it's the car/bedroom issue. It's not so bad now, when you can pick up an older 7-seater for £2k but when ours were little the only 7 seater was a volvo, which was out of our league.
We also had g, b,b,b, so it was 3 boys in the same bedroom, and DS1 really needed his space. 4 meant they always had someone to play with (great) but also someone to fight with (not so great). For a long time DC1,2 and 4 hated DC3 plus DC2 also hated DC4, so there was lots of trying to keep them separate in a house that wasn't big enough to do so.
They never complain about their childhood, but we do get a lot of we never had that/did that when we were young, directed at DC5.
Then we had 4 different schools for 2 years (that was fun), 4 lots of shoes every 2 months, and then 4 teenagers eating a weeks worth of shopping in one night!
That was followed by one doing Y9 SATS, one doing GCSE and one doing A levels 3 times. University visits, and dropping off/picking up every term x 3. It never ends. They are all adults and still really close, which I am really pleased about, but we never seem to have a day off which doesn't come with a request to give lifts/collect furniture/provide loans for deposits/take them on house viewings. If anything they are harder work once they leave home.