When I memorize tab, I forget them so easily in a jam. If I get stopped or cannot remember a note, I have to start over. I find it is so much better to start off with the chord progression of the song and sing it. Get the melody in your head first. Then I will watch someone do a simple break online where I can rewind over and over. Then I practice that break over and over until I hear the melody in the break. I have a looper pedal that I will use to lay down the backup with just vamping the chords. Then I will play my newly learned break on top of that loop. When I do this, I am a lot less likely to mess up in a jam. And if I do, I have that melody in my head and know where it is in my break, so I can just pickup up on the next beat. To me this has been a big improvement over learning anything via tab.
Memorization vs Reading Tab
@JoeB One has to have the experience to JAM before knowing thisā¦
And for that, you are ahead of meā¦ Warranting 5 GOLD STARS!
@WillCoop, I believe the best way to improve your playing is to go to a jam. People get really scared, but it is not that bad. Learn your basic 1,4,5 chords for common keys - G, D, A, C, and E. In fact, just learn the chord shapes for 1, 4, and 5 for any key and then move them down the fret board in order to change keys. I can post a video if you do not know what I am referring to here. Just vamp or roll quietly over those chords. Watch the guitar player to see when they change chords. You donāt have to take a break or play a lead. Just tell your neighbor to skip you. Lots of people do that. Then, learn one song really, really well and play it when it is your turn to kick off a song. You will be nervous. You will probably mess it up. But no one is going to point at you and laugh. We have all been there. If you wait till you are an amazing player, you will never go. Because in order to be amazing, you have to jam with others. 
In talking to older musicians about all the stuff I want to learn, they say you never feel like you have arrived. There is always something else to learn.
Jams are awesome! My family goes to this one family camp that has a huge number of bluegrass/gospel family bands. Almost every year they have one big jam session and all we play is hymns for nearly 3 hours. It rocks! Oh, and I memorize everything I play. All I have to do is literally play a song through once and it is practically burned into my memory. Iāve always been like that, and it is pretty nice, but stinks because I have a doubly hard time trying to sight-read notes!
Coolā¦ Yeah the video-graphic (both visual and audio) type memoryā¦ Donāt have it any longer. 
I think sight-reading and playing by ear are opposed to each other by nature. I think you have to work doubly hard to get skilled in both.
Hi
My thoughts and practice routineā¦
Sustained memory is achieved by consistently playing a piece/part over and over again until the need for tab becomes less and less.
Think of when you started drivingā¦ do you really need now to think about itā¦
When i start a piece/song, i like everyone struggle at first especially bluegrass as a lot of riffs and parts are very similar in a lot of songs so its more difficult to grab the tune
i get to the stage were i thinkā¦ ok i can now put the TAB away and only then by constantly playing the parts do i get to the stage where i no longer need to refer to the TAB and eventually i can start to speed up the track until it becomes like drivingā¦ i donāt think about it
Hope this helpsā¦