@SuperDunk You are right there we could win with conditions as low as 40-50%, as long as we are heavy favourites of a tie.
Not sure anyone has tested it, but I would tend to believe that dropping to a certain level of conditions would equal to an drop of quality of a player. Eg. 80%+ means full quality of the player (hence in green), 50%-80% conditions means somewhat 70%-90% quality, 30%-50% conditions means 50%-70% quality, and under 30% conditions means player may only play as half or worse as his maximum potential in quality. This could also explain why when we put it an excellent sub, or a first-11 as sub, in around the 60th minute, then that player tends to score a brace or even hat-trick within a short space of time.
Like all other managers, I also always play my best players for as long as possible for both their performance and motm improvement.
The difference is I would not spend 11 greens onto all first-11 to recover all to max conditions for the 2nd match of a day. Mostly I would use 4 greens to keep my best 4 players at max conditions and they will play for the full match (last match of the day, so no need to worry about preparing for next), 3 mid-high 80s% conditions to play full game and the lower 80+ conditions either play first half or come on as subs in around 60th minute, depending on opponents. They should all have around 70% by the end of 2nd match, and should be back to full the next matchday. GK normally would not require greens even when match is on high pressing.
The last thing that a manager needs is to exhaust most first-11 to 50% after 2 matches, then have to put in 2 or even 3 greens for each of them for the next day when fighting in a must-win cup tie.
This is how I would save greens when game-time for the worst few of first-11 could be sacrificed. There is no random factor in play here.