I had to write a note for somebody last week. It was not a very long message, only a few sentences, but I had a full-size sheet of paper to write it on. Since there was no need to squeeze the message onto a small area of paper, I decided to fill the page by writing in big letters. It was a nice experience.
Big letters are clearly visible (depending on how good your handwriting is). They have enough space between the words to avoid confusion (no accidental mash-ups of words), but not feel cramped. Although the note itself was not anything special, I still felt good writing it out. It felt like a luxury to get to do it.
I realize that it felt like a luxury because it is not something I often do. Again, I try to fit as many words and sentences on a page as possible. I try to be as efficient as I can, which will save on paper waste. That said, paper is not awfully expensive and if you feel better using big letters, it may be worth it to go through your paper faster.
This is something I never thought about until I did it on a whim. I tried it and liked it. I will try it again. All I can really say is to try it yourself. Try it once. Then see if it is worth trying again. You're not out much by trying, so what's there to lose?