You just nailed it Say you lost the roll for the double turn. but you have two rerolls, so you can first make your opponent reroll. Then If you are still losing the roll, you can now reroll. It's super powerful.
And also choose low enough so you can get the re rolls to turn and alternate to keep the player thinks only 5% of the time do they get it and don't be greedy with choosing it either
If your opponent is reading you correctly just roll the dice in your hand and don't look at it. that way he has the lowest chance to guess your number!