With the longer than normal "Wait" times afforded to specific classes and tiers of vehicle due to the issues resulting in the Matchmaker, I feel there needs to be a fairer alternative than the current "time-based" reserves. It currently means that those grinding through lower tier tanks, SPGs, and using Premium "preferential MM" vehicles are receiving less benefit. In addition, time-based reserves are also an issue for those players suffering from poor connectivity and server issues. In addition, it's more likely to encourage suicidal play and botting by poorly matched players.
To avoid this, surely it would be fairer to base their usage in the same manner as rental camouflage? I.e. Base them on a specific number of games played?.