Is training pointless unless you want 8* or 9* and are personal trainers pointless full stop?

If you need a 5* player isn't it best to buy one?

If you need a 6* player isn't it best to buy a 5* with 24 quality and then use a green pack or 2 to train him to 6*? I've watched dozens of auctions for young 5* aprox 24 quality players and normally they go for between 1 and 3 tokens. Highest I saw was 5 tokens.

If you need a 7* player isn't it best to buy a 6* scout for 64 tokens and use a green pack or 2 to train him to 7* Even trading tokens for cash it still must be cheaper

Is there ever a time before 7* for training, beyond a few skill points to gain a star? Is there ever a time for personal training?

To gain 75 skill points must cost 50-75+ green packs? That would cost 46-70+ tokens assuming no injuries.

With training theres no cash needed but watching adverts can get you 80k to 120k a day and money seems to be easier to get and more useful than green packs.

Am I missing something. I see stuff about power training and dont get the point? Any info would be great as I must be missing something.

Thanks