Thanks for the praise Edmund. CCsoccer, what i'm trying to say is that with the 2 subs per half, it would take off tired players, if there was to be an injury and it was for the whole game, it would count as a sub, however if it was a temporary one where a player would come in for a few minutes till the injured has recovered, it would not be counted as a sub. But thinking about i think that would be complicated in ruling whether a player is eligible to play for the whole game or not. So how about 3 substitutions during each half, and unlimited at the end of the first half. That sounds fair to me. I also like Edmund's theory of a player being limited to coming off the field twice but the thing is that it would be a major stress on the officiating crew on keeping up with who has been on and off. I think the 3 subs during a half and unlimited at the half is a perfect solution. (it could be more but i'm just making a generalized statement on the topic).
CCsoccer also to reinforce the main idea of the topic, limiting subs will accomplish a lot in high school soccer, it tests the players stamina and their ability to perform through a rough time instead of just releaving himself everytime he feels tired. A good example is let's say you are a A school and you are playing a AAAA school, you have 16 players total, while the AAAA team has 30 players total. Now let's say that the skill level of all players on both teams are equal. With the current rule of unlimited substitutions, if you see your players get tired, and you only have 5 people on the bench it is going to be hard to keep fresh players on the field, now the AAAA school will rotate their whole team out almost in rounds of 3 every 5-8 minutes, whose team do you think will last longer, yours or theirs ? I hope you can relate to what i'm trying to express through this topic here, with limiting substitutions it will bring teams to an even playing field and test out their skills in stamina and so forth and their ability to play for 80-90% of the game in good condition.