Personally long am/short pm worked for me as I couldn't find the right A time to get a longer nap in the afternoon.
We just kept pushing out the first A capped the nap at 1.5hrs then did a CN 3.5hrs later. Some days she'd refuse it, others not. I had to keep capping tha CN from 30mins, to 20 then 15 as the first A time got longer and to stop the day getting too long iykwim?
We started off by doing:
Wu 6.30
A 4hrs 15mins
S 10.45-12.15 1.5hrs capped
A 3.5hrs
S 3.45-4.15 30mins capped
A 2hrs 45mins
BT 7ish
Then we got playing around at BT and nap refusal so quickly jumped to...
Wu 6.30
A 5hrs
S 11.30-1.30 uncapped
A 3.5hrs
Tried for a CN often refused. If she took it she had 15mins max
BT either 6.30 if no nap, 7 if she did but often didn't fall asleep until 7.30
This caused OT early WU's after BT so had to push out the first A even more. So now we're on:
Wu 6.30
A 6hrs
S 12.30-2.30 capped
A 4.5hrs
BT 7
I had to do the set nap thing in the end as she woke early more often than not. So I know I've said the times were wu from 6.30 but she used to actually wu around 6, but we didn't get up and start our day until 6.30. I've noticed I do get a shorter nap now (1.5hrs) if I wake her at 6.30 as the A isn't as long. Probably means she's looking to push out that first A by another 15mins

Hth xx