Quantifying Rewards

There is a Tosfos in Sota 11a that quotes a Tosefta. The discussion there is about G-d's kindness and the opening chapters of Shemos. It explains that Hashem punishes for up to 4 generations and rewards up to 2,000, a factor of 500:1 ie G-d rewards 500 times more than he punishes.

Miriam spoke Lashon Hara about Moshe Rabbenu, and got Tzaraas (mis-translated as leprosy) so was sent out the camp, but the Jews waited in the desert for a whole week until she got better before they moved on. And this is not just because it takes a week for someone with Tzaraas to get better, as there is no requirement to wait for their recovery. So why did they wait then?

The Tosfos says that the waiting for a week was a reward for what she did in this week's Sidra:

"וַתֵּתַצַּב אֲחֹתוֹ מֵרָחֹק לְדֵעָה מַה יֵּעָשֶׂה לוֹ - His sister stood from afar, to know what would be done to him." (2:14) - Some commentators point out that there are 7 words in this Pasuk, corresponding to each of the seven days they waited for her.

This is fine, but the comparison is superficial at best, how long did she wait already that they waited a week?

We can quantify this. There are 168 hours in a week ie they waited that many hours for her, and we established that G-d does kindness by a factor of up to 500. 168 divided by 500 is 0.3something or other, or a third, of an hour ie 20 minutes.

Miriam watched Moshe for 20 minutes!