I forgot something else.

Speech balloons are... a restrictive shape. You don't get "free word choice" when writing dialogue for speech balloons - you need to break your sentence up into "lines" and each line has to be approximately the same length. Longer bubbles are less restrictive, because you have lots of words on the line, and can normally use a synonym to change something on the line to get what you want... but long skinny bubbles tend to look bad in-panel. I get away with it by cheating with "text blocks" when I'm expositing, but in general it's bad practice to do too much, because a big text block draws the reader's eye away from the images.

Panel 4 here is an example of this. I don't really have space next to the art to put the lower bubble into the frame, so it has to escape the bounds a little to make room. In an ideal world, I would write "100" I'd write "a hundred" - but there's no way I can fit that in. I wanted to write "a sunken temple" but that's too much to fit into the line, so I have to pick something shorter. I want to write "she woke up with..." but again, it's an extra word I can't afford to spend.