Fully agree - from 2023:
If i assume 10 minutes as average match length we talk about 1.200 - 1.500 minutes (with boosters) in Air RB to get the 710 k RP. That’s a little bit faster (~ 25 hours) but i had already a level 75 crew.
If you have the choice, passion and you want to get a quick 1 vs 1 advantage: Buying crew skills is the easiest way to get the upper hand in rather rare 1 vs 1s.
If you want to save the money I always recommend to use a good low tier aircraft (which is a reliable and stable SL / RP source) to build up crew skills before you get above 3.0.
Even if it takes time - it is way more frustrating to get constantly clapped due to missing crew skills with a linear progress than taking a sidestep and use a low tier bomber to build up crew points (at the right place) in order to use full potential of an aircraft.
Example:
I earned the event Bv 155 (as first German plane) - and managed to lose 20 planes in the first 20 matches. Mainly because i was unable to adopt my play style - so either i blacked out and got killed or i blacked out and exceeded the very low rip speed. The 20 matches allowed me to research the Ju 88 A-1 and i flew ~ 150 mission to build up crew points. As a result i lost just 30 Bv 155s in the next 150 matches.
Have a good one!