I almost always check my OG and FG when doing extract, although the OG more often than not tended to come out a little low (probably partially to do with insufficient stirring after topping off the water, or topping off the water too much because I never knew my pail markings were mostly too high, thanks HBT!). I would almost always top off the water to the (inaccurate) 5 gallon mark figuring that if I put in the exact amount of extract then there would be no explanation for it being too low except for racking loss. I'd write down the number, and whichever day that I wanted to bottle I would check the FG and consider how much it dropped before I decide to go ahead and bottle. As far as I can remember, it was always low enough by then for me. I rarely check the gravity before I am ready to bottle, I probably did on a lager or two since they move slower. I just don't like opening the fermenter. I never felt like getting out or making a little bit of sanitizer just to measure the gravity between OG and FG (things have changed). Due to the seemingly nonsensical OGs at the time, I never worried too much about the outcome.
I do try to get my brewing friends to measure at least their OG and FG, even just for my own information. At least once I pointed out a FG that was too high to bottle, and it tasted like it too, so we put it in a secondary (it might have needed one anyway, can't remember).
Now that I have correct markings on my pails, and having thought more about how I would adjust my recipe or wort concentration when doing AG, and wanting more to brew a better and more consistent beer, I will not care how close I get to 5 gallons, I'm going to adjust the post-boil volume to land the right OG in the boil kettle and then just ferment whatever volume I can manage to rack out. That way I'm not leaving behind denser wort in the BK that could have possibly made it into the fermenter if it were thinned out to start with.
Another point is that the FG won't cause bottle bombs if it is kegged. If it tastes good and gets kegged, that's all that particular batch matters (to me anyway). I'd still encourage measuring it but I wouldn't be terrified if it was 1.020-1.025.