I don't understand the reasoning for why though.
We know the rate goes faster, we know to which days this value applies (only affects like 7 to 14 days of growth, somewhere between). We have multiplier statements, one shot statements (which is also stated to be based on the growth), in a fight that are Saitama vs Saitama in both fights.
I can't even see the logic behind them though. I'm just trying to understand. (might be useful for later as well etc.)
I already tried to explain it to you clearly, but I suppose I will try one more time to simplify it since you are being respectful about it.
It is true that we do not have explicit evidence his rate of growth slowed down.
We also don't have explicit evidence it didn't, and don't have explicit evidence it always sped up.
Garou's exponential rate of growth reflects Saitama's when he was early in his journey.
It's clear that when they both started pushing past their limiter, it was exponential.
We do not have explicit evidence that this trend continued forever.
We do have evidence that their rate of growth can change since it spiked due to emotion in the Awakened Garou fight.
So essentially, while we have
hints towards what his growth may have been like, we have no actual proof of the rate overtime, except for early on, which we can't extrapolate forever due to the rules of statistics.
Therefore, we essentially don't know the exact rate.
Since we don't know for sure, we can't assign an arbitrary number such as 2x.
We can, however, safely say that he grows stronger constantly. That is fine to list.
To claim it's exactly 2x per day is an assumption we simply can't make without far more evidence.