Some geologists have developed an all-caps sort of handwriting where everything is concise and exact. I was taught this in drafting in 7th grade. I couldn't really do it then, either.
But I'd like to think that my handwriting is generally legible and that when I write in all caps, it doesn't look like I'm in the third grade. I haven't had too many people chase me down after the fact to interpret my field notes. Of course, there are times when it's raining or cold and the succession of pens I keep as warm/dry backups in the depths of my clothing have all failed and I'm in a hurry. And then it takes a special frame of mind for me to recreate what the hell I was trying to say.
The real problem is numbers. Words you can often figure out from context, or failing that, figure that a particular phrase was not particularly earth-shattering. Numbers may have some context ("that pH couldn't possibly be 17!"), but often it's critical to get the correct number without guessing at a reasonable approximation.
I am very careful that my numbers are distinct so that I can never confuse them. For me, a 1 is a single line, a 2 has a little bubble in the lower left part, a 3 doesn't have any bubbles, a 4 always has hard edges, a 5 has a pronounced sharp top and curved bottom, a 6 always has a curve to it to distinguish it from a "b", a 7 has a little cross through the center, an 8 is... just an 8, a 9 has a closed and rounded top (to distinguish from a 4), and a 0 is just a 0.
Hmm. That may not make any sense to a reader. Here's what my numbers look like:
Of course, the problem is that I know what my numbers are supposed to look like. Then someone else comes along to interpret my handwriting while I'm out, and then they think my 7 is a 9, my 2 is a 3...