We have automated follow up on days 3 and 7 on Domestic quotes, days 7 and 10 on Commercial quotes. After that Domestic quotes get personalised follow up at 1 month, 2 months and 3 months - if no reply by then, archive quote. If they do come back after that you can then go back on the quote and see if its still valid for current work required. Commercial get follow ups at 2 month, 3 month and 4 month by personalised emails.
This works for us as Tree Surgeons. A lot of domestics get 2 or 3 quotes, so you give them time to make a decision. The ones we don't get at day 7 usually reply by 2 months. We also send mailshots every 3 months, that works too - Gentle reminders for hedge trimming and tree work.
Personally too much chasing puts me off, i need time to decide who I am using. Why if you came yesterday and the quote arrives in the evening, do you need to chase me the following day?