It is fine to have someone call for you. I would do it, but I think you live a long way from me.
I never took the laminated sheets to the yard as one cant fold them up and tuck them in ones pocket.
I think one can get a recording and listen via one's phone but i always need my mnd on the horse. Plus, although I rode some quite advanced moves, I never ever rode a complete test from start to finish as my energy and concentration and memory did not stretch that far. So I would split the test in half.
I liked the big school, especially one day when I did it on a new field with white boards, so there were no fences to scrape my leg on. The RI was astonished. She said most people wanted a fence.
For me, reasons why I prefered the big school - I had watched the Olympics dressage. The walk on the diagonal is longer in a big school and then I dont feel cramped when it comes to canter before the next corner and when we get to the long side still in canter, I just told the mare she could go forward as fast and powerful as she liked. You cant tell a horse that out hacking or in a small school. Trotting up the centre line to halt at X is also better in a big school. I find it hard to get the trot active enough if I am turning up the centre in a small school.
But there are other things I do ask out hacking. Trot halt trot and trot back 4 and trot again are very good for reminding a hack like Ella (who cant bend) that I expect attention and compliance.
Exactness in a dressage test is very useful as one can dictate that out hacking too.
Just to clarify, I was a mature rider who had learned to ride late in life and i was really exciting to get these new skills. And work up through the tests on a safe pny. It wasnt to compete or to impress anyone. Tho the YO told me he had seen me from the office window and was amazed.