0- In practice match the condition lost is 9-10%, while in a real match it depends... Generally goalkeeper loses less condition than outfield players. Also players with arrows lose more. If your mentality is hard attacking/defending, play high/whole pitch pressing, man-to-man marking style, they lose more condition. Also better morale usually produces better training sessions.
1- younger players usually train faster. There is an average value at which a player trains.
5- upgrade your training facilities, you should get a certain amount of rests in every 4 days. Make a sub during a match you've attended to get a rest. Watch vids, if you play on phone.
That's all I can help....