I read on another thread about your great progress over the last couple of weeks OP - I'm really pleased for you.
I think the 234 is a guideline which you adopt to suit once on 2-nap days. Remember that many vhikdren will be having 2 naps for over a year, so their awake time needs may change in that time.
Mine always had two exactly 2h naps (I would wake after 2h, would sleep for longer if left) so I had pretty exact awake times to go with it.
We had a 7-7.30 wake time, 9-11 nap, 1-3 nap and 7-8pm flexible bedtime.
So it was therefore 1.5-2 / 2 / 4-5 for us. The flexible bedtime was dependant on if baby was ready for bed earlier, but the aim was 8pm.
I think she could manage the longer awake time in the evening because she was having 11h uninterputed night sleep (usually) plus had 4h daytime sleep, so simply didn't need any more and was happy awake.
I'm actual fact I think a 9-11 and 2-4 routine would have naturally suited her better - giving 234. It's just this wouldnt wouldn't have fitted in with my school run at 3pm. So she just got used to fitting her 4h naps in during the school day, because that worked for us.
Ive known other people who develop 333 routines, or 233 or 244 - whatever works really.