Experienced coaches know how important the rerolls are, but it is always difficult to explain why rerolling only one roll in a turn can make the difference between victory and defeat. I will take some examples and use the proba calculator to show the importance of rerolls.

One free SPP
Imagine you play elves (or any other team with AG 4 players) and you want to gain one SPP with a "safe" completion (quick pass, no tackle zone, etc). You just have to roll two 2+, it seems easy but...
without reroll you have only 69.4 % of success. With a reroll, it is better (92.5%) , but you will miss about one time out of ten. The "free" SPP may be really expensive when you don't have any reroll left.

Chain 2d-blocks
Another frequent mistake of beginners is to consider a 2d-block (without the block skill) as a safe roll. You have indeed about 12% risk of suffering a turn over on each 2d block. And since you always expect to knock out some opponet's players, you may be tempted to make several 2d block even if your players do not have the block skill. The following table give the percentage of not suffering a turn-over because of the sequence of 2d-blocks.



number of 2d-blocks 1 2 3 4 5 6
without RR 88.8 78.8 70 62.1 55.2 49
with a RR 98.7 96.5 93.5 90 86.1 81.9


So doing one 2d-block without a reroll is almost as dangerous as doing 5 2d-blocks with a reroll.

Scoring in the last turn
This is the last turn of the game and you must score, playing humans. One of you lineman has the ball, and scoring seems really easy : you just have to do a go for it and a transmission (2+ and 3+) to give the ball to a blitzer, then the blitzer must do 2 go for it (2+ and 2+). Without a reroll, you have only 38.5% of success. With a reroll, it is 70.7%. It is nearly the double.

Conclusion
Keeping at least one reroll for the key moment of the game is the key to victory. A good coach is a coach who know when he must spare a reroll.