or you could go for three trainees:
1 big guy who has his outside skills too low
1 SF who is sort of in balance
1 small guard who has his inside skills too low
now you do single position training, switching between inside and outside trainings. you strengthen three roles on your team, the big guy faster his inside skills, the small guy faster his outside skills, the SF marching in balance. 2 of the three can be used competitively (semi-competitively in the case of the SF) in each week. I think it's better than raising 3 SFs at the same time like BC Töröö does - who needs 3 SFs?
but i things this brings some trouble then building 1-2 SF with your normal training, because training switches are difficult:
1. You only have one trainee who is strong at your current training program, but up to three games.
2. You have to move your C/PG out of the trainingsspots, if you train that position
3. When you buy your C/PG, you couldn't use that much founds, because you need starters for two non training positions instead of of one
4. Eventually you need also lot of medium trainee, who could be integrated in two position training, mostly for rescueing mins because the most two positions stuff works with the PF's.
Thats why i find iit is easier to integrate just one SF trainee into your training, instead of building then normal(if you plan to switch training you could start rigth away with 18 else i would look that someone else makes the first steps in the opposite training - but even a training switch after two seasons ain't that bad like mentioned before but switching all the time is complicated).