But what can you do to reduce the need of a page turner dramatically?
What about finding the places in your score which have at least a couple of beats of rests for one hand? This hand could turn the page while another would continue playing.
You can also turn the page by leaving out some of the non-essential middle parts. You see, the most important voices usually are soprano (the melodically most developed voice) and the bass (the foundation of harmony). That's why leaving out tenor and turning the page with the left hand sometimes is possible.
You can also memorize a few measures before the page turns and after them to play it fluently without looking at the score and turning the page later.
Finally, you can photocopy the score and shrink its size in half so that more pages would fit on the music rack without the need of turning them (although it does give some strain to your eyes).
If you play from a tablet, there are special apps which facilitate page turns. They have wireless pedals for that to press with your toes.
Whenever you need a person to turn the pages for you, make sure he/she turns them at least a few beats in advance. Memorizing the transitions helps to ensure it will go smoothly.
Of course, don't forget to make sure your photocopied pages are in the right order. I've seen some circus worthy movements by the organist and assistant during the performance when they're don't.
Usually people who are poor sight-readers are poor page turners as well for obvious reasons.
What's your experience with a page turner? Do you always need someone to stand next to you and do it for you? Have you worked with a page turner who was so nervous that you wish you didn't ask for his/her help?
Transposing Sequence in A Major: I64-V9-V7-I