I was working under the assumption that each side had an equal number of players on its team. I guess if Luxembourg has 30 players and the US has 200 players on the sideline, this would be a problem.
Is there really no limit to how many players can be on a World Cup team?
And just to be clear, I was suggesting allowing subs only in deep overtime, not all game long.
SD
Yes, teams have a limit on the number of players.
Ok, if you want to allow rolling subs then you shift the emphasis on who needs to attack. As it is, the better team has the incentive to attack lest they risk going out in a penalty shootout. This gives the weaker team the opportunity to counter attack.
Allow rolling subs I extra time and the stronger team in theory has more incentive to defend and flood the pitch with different good players in extra time.
Personally I think the former scenario is preferable.
In small leagues like the one I described, there are really no regulations like that. The professional leagues of course have limits.