I've played other time based games, but only today I realized that they usually have two timer reduction options:
1) The paid timer reduction similar to the [Reduce Timer]-button on PT's skill training page
2) The free timer reduction which becomes active only during the last 5 minutes.
I think this option usually exists because it tends to keep people with the game.
Current suggestion would be to add such free timer reduction option to PT's skill training page. I understand, this could drastically speed up training times for beginning players. BUT for the more advanced skills this would hardly make any difference (5 minutes on 5 days is negligible), so it would not be disturb the balance.