I'm certain that it's more than 50-90 hours for 1900-2050.
I study a lot. And my results have been showing the fruits of those labors as I have become much more consistent against lower rated players.
I personally think it will take me several years to gain the next 300 rating points. I could be wrong, but that is what I suspect.
What is your study regimen Chris?
Coons prepares especially well for games on Wed & Thurs because he knows in advance who he's going to be playing and generally has several games as both colors against them to look at.
He uses Chess Openings Wizard but a bunch of other stuff too.
Here is a rather detailed post on my blog...