LOL you can have that one if you like 🙂
But seriously, "refinement" is not really the issue IMO, flexibility is. A key characteristic of triple spool, is that fan RPM is fully independent of core RPM, because it's on a separate shaft. This has long been commercially advantageous to RR, due to much lower development costs for simple derivatives.
But as you rightly pointed out, RR don't say to customers "triple spool is best because it's good for RR" they have to find another way to say it's better 🙂
With triple spool, a common high/intermediate pressure core (i.e. the difficult/expensive bit) can be easily (and therefore cheaply) scaled up or down, without significant modification, just by throttle push. Only the (separate, lower cost) LPT need be tweaked to achieve optimal fan RPM at a range of throttle settings/BPR.
GTF can achieve the same characteristic, but via gearbox setting, instead of via LPT setting. It's no coincidence, that RR are designing their gearbox, to work at a range of different ratios.
Last edited by Sonikt; 25th Apr 2021 at 00:15.