I also wrote programs to run long equations on my calculator. This wasn't forbidden at the time because it was too early, I suppose. Regardless, you had to show your work to get credit anyway so they just functioned as a way to check my work instantly.
I had a lot of fun writing little programs to help out on long arduous problems though. I wish I had all my TI programs.
Unless the exam allows notes, it can make sense to forbid using programs that are already stored and require to write the program during the time needed for the exam if you want to do that (even to program it to show the work if you want to add that into the program too; I think someone once did this), then it can be OK to allow it, I suppose.
I had a lot of fun writing little programs to help out on long arduous problems though. I wish I had all my TI programs.