I have the changes memorised to about 400 tunes. I don't portend to KNOW these songs but if they are called I can comp and blow. 
 
 
When I was doing a long commute I used to keep a homemade fake book on the seat beside me, hum the melody as I'd memorise 4 bars at a time. 
 
The Autumn two minor seven five seven one.... 
 
It helped that I was playing 2 nights a week with a leader with a huge book. 
 
The memorisation thing became an obsession for a while, I was closing in on 600 tunes but I would have to review them constantly.  
 
Now it's evened out and I review less rigorously. 
 
The best parts of the process were not needing a book on gigs and the recognition of repeated harmonic patterns between songs. I think in chunks of chords now instead of just one or two. 
 
I've also named progressions for quick recognition. 
For instance I call VIm7  /  II7  /  IIm7  /    V7   
a FINESSE FIVE because it appears to be going to the FIVE MAJOR. 
 
I can say to folks I play with regularly, "lets give this the LAURA ending" 
 
Gotta have a hobby.