Let your intuition guilds you!
Memory trainers use all the techniques they feel most comfortable.
When I build my pao, I had gone through the process like u did. I read others example and then started my own. I used nearly half year and found out I wasn’t doing well in recalling them. One memory league player reminded a fact: skyscrapers built from ground. If u can master p a o either one well than u can start on next level pa, then finally pao or others.
To examine ur skill reciting pi is a good idea.
Back to track, all the three ways u suggested, I tried and included in my pao. I mean it is not necessary matters. Just choosing either way u feel good with it and when u do testing readjust it to what u feel better with.
The above was my training record in Pi with PAOX (similar to pao I don’t want to mix u, so no explanation here).
As you see PAO sometimes get into some weird combination, but training will increase ur connectivity.
The app I used for training numbers.
To be honest, I am no memory athletes, and I am just a fans of analysis memory techniques. my skill on memories 80 random numbers is around a minute.