Definitely! It's part of the reason my handwriting is so sloppy, because if I don't keep up with my train of thought, I end up back at square one. I also like typing because it's more uniform and the margins are automatic (My notes in school are crammed with notes in the margin... mainly because I have doodles everywhere else

)
I also find that when I want to elaborate, I cant because I have a different, good thought coming from another direction and I have to get THAT one down or risk losing it all together.
INFJs dont need extreme sports, trying to write a paper is harrowing enough sometimes!
I've actually gotten into the practice of writing a (very) shorthand note type thing to remind myself of the first thought while I follow the second.
More often than not, though, it's incomplete, like a question mark hanging off of already cramped chicken-scratch notes.
Also, I am often unaware of my own convictions as well.
There are a few, however, that I just don't feel like sharing with the rest of the world, namely, because they aren't up for debate. My mind is made up, and I know people will ask questions, and try to argue... etc. and I just don't want to go there. Other things, just don't seem like they need to be shared. No one cares about my weird obsessive reasons for eating lunch at a particular time, or why I prefer one pair of socks over another, so unless I'm on Ti/Se blowout mode (lol) no one will hear about it.
Still other things, I am perfectly comfortable sharing, and others aren't sure what to make of it at first because the subject isn't something you "ought" to discuss... I am the most secretive queen of TMI ever.
That was a pretty good example of a "thought tangent", actually...