Matty, thanks for your tips
Kaji, as i said i have a somewhat similar method: i visualize 5 buddhas of a silver color in a position like the 5 dots of a playing dice; then, each time i say "Namo Amitabha Buddha", i will "highlight" a Budha...my mind-eye will be running through each of the 5 Budhas (each Buddha = 1 recitation).
Then i will repeat the process but with 5 golden Buddhas. Using the visualization of silver Buddhas then golden buddhas is a easy way to reach 10 recitations whitout counting them (couting is boring sometimes
5 silver Buddhas + 5 golden = 10 recitations.
After doing a set of 10 recitations i will bend a finger.
This way, by visualizing & using fingers for each group of ten, you can reach quickly 100 recitations without counting.