Yep - every 3/4 takes, maybe more often if there's a lot of string bending involved.

I recorded and co-produced the one and only Billy Higgins (very famous jazz drummer) in my 16 track studio in L.A. a long time ago.  His bass player who was a popular pro was out of tune when we first started.  I had to tell him and he was not pleased with my comment.  He did tune up and that fixed the problem.  Back then, we did not have anything to fix that kind of issue in the mix!   

Rimshot

I'm doing mine practically every other take...I'm still learning as I go.

Every 3-4 takes, really?!?! You guys need some new strings or a new guitar... I'll tune at the start of a session, then maybe a half way point check, but that is just about always spot on. And it's only off if my strings aren't fully worn in or I did a major tune in at the start of the session.


Speaking of out of tune recordings, I have a rough demo/scratch track where the chorus is about 50 cents higher in key than the verse. The parts were recorded on different days with different guitars and I think I did one of the tuning buy ear cause I was lazy or something. I feels almost like your typical semi-tone key change, but not quite cause it's only half way there, haha. Fortunately, the recording is purely there for the purpose of writing down the song structure, so it doesn't really matter.

My understanding is that it is good to use the same tuner on all the string instruments too (e.g., guitars and bass).

t

Good point T  

I remember MANY years ago in high school we all used the same tuner (the old rotary strobe tuner) to tune all the instruments the same.. I could see one being a little off from another turner really screwing with things.

Yesterday I was tracking for a producer and we tuned for each part depending on the position of the part on the fretboard. This helped to make up for intonation problems.  
 
Ken
 
 

It depends on a few variables.
If environmental conditions have changed radically, I watch it pretty close. This seems to be a bigger factor here in Fort Worth than it was in Denver.
If I am using new strings, I check every take. Although, I usually don't even try to record until a set of strings has had about a week to settle in.
Proper setup is also important. For instance, my Rogue resonator shipped with the strings and truss rod somewhat slack. and the machines were a little loose. It floated like crazy. Once I realized this, I tightened everything up, and it has become a very stable instrument.
It's good to check often, but if you have to make frequent adjustments, there may be an underlying problem that needs to be addressed.

Check your tuning as often as you can stand it is the best answer. Reasonably speaking, I think I usually check it every 3 or 4 takes but that's because I set up my own guitars and they usually stay in tune pretty well. A lot of wild string bending or whammy action will usually require more frequent checks.