You can go to https://steemd.com/@nandotrif to check your numbers.

Mana, like voting power (used to) replenishes in 5 days.
Or, in other words replenishes 20% each day (prorated/calculated per block)

The thing they are not telling you is that the minimum RC mana was set SOOOOO low, that a newbie account can vote twice every five days. They could never post or comment. Their maximum mana is lower than the cost of those operations. Meaning, waiting for things to stabilize meant nothing.

Even i, with a decent account, 1.5 MVests, don't have enough mana to do the manual voting and commenting that i used to. The 10x (change written about above) will be enough for me, the 5000th largest account. I am pretty sure they will up it to 100x before all is said and done.

Further, mana should never have been based on a linear formula.
The difference between a super active user and a minimal user is actually very small.
So, the line will quickly get into territory where you could never spend it all. So, why bother at all?

The only reason is bots. And those need to be computed separately.