Currently I started with pass because I have only 3 players to train, I don't have players to fill the slots for 1v1 right now.
Not having enough players to "fill the slots" shouldn't matter. If you are serious in training players, having the most efficient training is what matters.
anyway i want to try strange builds, its ok if its not the best to do.
There you go, you've got your answer mate. IMO games are for enjoyment, so even if what you love to do isn't the most optimum, it's totally fine as long as you don't mind the things you're missing out. In my previous team, I really loved the NT (particularly the U21), and I would go all out on buying up these former NT/U21 players to fill my roster (most of them were past their prime and had skills dropping here and there). It was terrible for my finance, and coupled with the NT player I was training and a small arena size (I didn't expand it and by the time I knew it was important, I didn't really have the funds to do so), I was constantly going in and out of debt. But I loved it and it gave me a sense of purpose of the game, so it's totally fine to try inconventional builds if you love to do so.
why ?
As for why, it's because usually people train the faster skills to be high enough so that the slower skills can pop faster than their usual speed. But it's just my personal preference of not training passing that way. It's totally fine if you want to do so.