I disagree (my anecdotal estimate would be around 1/3 do quickly, and 1/3 do "slowly" i.e. within 3-5 years), but those who do can still accelerate the process

I disagree (my anecdotal estimate would be around 1/3 do quickly, and 1/3 do "slowly" i.e. within 3-5 years), but those who do can still accelerate the process by reading documents like this, no? People who can self-teach still benefit from learning materials.