Nexus... good choice in literature there. Unfortunately I haven't gotten too into the series yet due to mostly time and some part money.
I think what B-wayne said was important. Everyone learns at their own pace, others have different tolerances for fear, risk, and what ever else.
My story is: I wanted a bike. So I found this forum, read everything. I took the MSF course, got my license. I found the bike I wanted, and dropped it while stopping suddenly while test riding it in the parking lot ( a good argument why msf should use sport bikes than are not so low to practice on). I later bought the same bike
I was riding the next day to various places. The day after I went to school with it, which required a little rush hour, some open freeway and some busy streets. I also learned the amazing thing called "lane splitting". The bike pays for itself once you do it the first time and get where you want to go 1000% faster than you would in your car. I thought 70mph looked like 40 on a bike. I still think that's wierd.
I also thing nexus' advice is spot on. I really think fear is the number 1 enemy to learning. I tried skateboarding, rollerblading and bmx and was terrified trying all of those the first couple times. To this very day I can't do either worth a **** and a half. I had nothing but a "reasonable"* amount of anxiety learning how to snowboard and ride a dirtbike and streetbike. I consider myself skilled enough and those things. The things I can do well are similar to the things I can't so I concluded it's the fear that held me back... and still does.
*"Reasonable" anxiety is just enough fear to keep me aware of my own mortality and thus keeping me honest with myself about my limits.