Its a sales technique for me. Lets say they get 3 quotes. They want mowing, pruning,weed and fert, aeration, and leaf cleanup.
company 1 offers 50 per cut, 250 each pruning, 65 each fert and squirt, 450 for aeration and seeding, and they bill per hour for leaves.... paid when completed each week.
Company 2 offers just about the same prices, but bills once per month when services done.
Company 3 offers a monthly equal payment over 12 months which in most cases is cheaper in the customers eyes. Monthly payment around 350 per month in this case with moderate leaves.
Depending on when the job is sold, your break even point (the point where the income from all three companies would be equal) is about 7 months out. I have found that the income per month isn't a significant difference most months except pruning months and September.
With the cancellation clause, there are several ways. The software that I use has an installment option which assigns a value to each and every service you do at the property. It keeps track of everything and gives a running total. It also keeps a total of the "installments" paid. Agreement could be worded that all services completed at the time of cancellation would be tallied and compared to what was paid and the balance is either refunded or paid. Its not the exact, but for these purposes, it should suffice. Or, just give a 2 or 3 month cancellation fee.
Again, its just a sales tactic. No benefit other than that.
By the time you can make ends meet....They move the ends.