Well, I have to disagree here. Personally, when I am playing a round that is not in a tournament or for cash (small cash, I don't play big money matches
I always know my score and I set goals for the front nine, back nine and total score and I track my progress. The reason I do this is to PUT pressure on my (I WANT to go into the 17th knowing I need par par to break 80). For me it helps to get used to playing like this (under pressure) because then when I do play a tournament or a cash game the difference in pressure isn't there, or not much of a difference anyway. I have seen/played with a number of good players with nice single digit or low teens handis and I watch them crumble under the pressure of tournament time because they aren't used to the pressure...
That said, if you don't plan on playing in pressure matches then absolutely don't keep track of score until after you are finished. And definitely play smart - when trying to break 100, remember that bogie is a great score, don't forget that! Bogie, bogie, double, double, bogie, double, par, double, bogie is 12 over through 9. Double that and you break 100 easy. You have to avoid triples (or worse) to break 100. Breaking 90 is just a few doubles becoming bogies. You can do it!