Hi Mummybare, the reason for stretching A times was short pm nap. From memory we were doing a nap at 9:30am, letting her sleep as long as she would sleep (varied from just over an hour to over 2hrs but I would wake her at 2hrs max after a couple of bad experiences with super long morning naps), and then no matter how much I stretched the second A time we couldn't get more than a 40min pm nap for more than a day or 2. I think we were up to over 4hrs A time.
What changed was going to set naps which meant a shorter 2nd A time; and moving bedtime from 6:30pm to 7pm. I think once her body clock "knew" that she had to stay up til 7 she "knew" she needed a longer afternoon nap. Another upside was that WU moved from 5:30/6am to around 6:30am. This took a while (over a week or 2 I would say) - previously if she'd had a later bedtime one night she still woke the same time as normal in the morning so it was interesting that after long enough on a set routine her body clock caught up so significantly.
I'm speaking from the place of a fairly textbook baby, who really really needs enough sleep - it's like she has 2 different personalities - the lovely happy baby/toddler who has had enough sleep, and an overtired one who is really hard work and not at all happy.
We had a couple of months on the first set routine when things worked pretty great, and then she started catnapping the morning nap fairly frequently (around 9 months I think) and that's when I moved the sleeps a bit later. Now, we would get a short morning nap once a week or so (and when that happens I move the afternoon nap forward 30mins and we always get a good pm nap), and a short pm nap probably twice a week. Plus, if we're anywhere other than the cot (or portacot if at someone else's house) eg pram, car, she only sleeps about 35 mins. And, we do get the afternoon nap refusal around once a week/fortnight.
So that's my experience. I'm a bit of a set nap time advocate as for us it has worked so well. Also it's a while since I read the BW books but it seems to me that much of the info on this forum about A times, how long is an UT vs an OT nap etc is based on people's experiences but not what I actually remember reading in the books so just keep that in mind, because it's easy to read something and think it's a "fact". I found the BW approach to dealing with a newborn baby, how to manage feeds, get into positive sleep routines etc so incredibly helpful, but I personally think there are other books and resources out there that are a bit more helpful when it comes to older babies and routines. Again just my personal opinion, so take it with a grain of salt just as I recommend you take all opinions!
Oh, and even though I am such a set nap advocate (ha ha), one day last week when DD was just miserable with accumulated OT from christmas and all the breaks to her normal routine, plus a cold, that I left her to keep sleeping past the 1.5hr mark for her morning nap, and she slept 3.5hrs! She's not napped that long since she was a teeny tiny newborn. So she didn't have a second nap and I put her for EBT and she slept 13hrs overnight! So just showing us nap nazis also show flexibility when our bubs need it ;-) It has taken until the last 2 days to get properly back into routine after christmas and finally she's happy again. Some bubs are more affected by colds, teething etc whereas others don't notice it. I was telling a friend about the super naps and nights we got when DD was sick and she said colds always mean less sleep for her kids! I hope your LO is on the mend.