Billing
Following up billing quotes that went quiet
Most billing quotes are not rejected. They are ignored, by a homeowner who meant to reply and got on with their week.
That means follow-up is not pushiness, it is finishing the job you already did for free when you measured and priced it.
Two nudges do nearly all the work: a short one a couple of days later, and one about a week after that. Beyond that you are annoying people and the return falls away.
Keep it human and specific. "Still want that invoice on Oak Street?" beats a marketing email every time.
The reason it rarely happens is that following up requires a list of who has not answered — which requires the quotes to be tracked somewhere other than your sent folder.