The estimate isn't the end of the sale. For most homeowners, it's the start of a comparison that takes days.
A roofing estimate almost never gets accepted on the spot. The homeowner is collecting two or three quotes, talking it over with a spouse, checking a budget — and somewhere in that gap, whoever stays visible without being pushy tends to win the job, even against a lower bid.
By the time you're back at the shop or on the next job, the estimate you just handed someone is already competing for attention with two others just like it. The contractor who's still on their mind when they finally decide is usually the one who followed up — not necessarily the one who quoted the lowest number.
Following up on an estimate from three days ago competes with today's actual jobs, and today's jobs win every time — they're right in front of you. “Follow up with the Petersons” becomes a mental note that gets bumped by whatever's more urgent, and by the time it surfaces again, they've often already signed with someone else.
Automated follow-up handles the timing and the consistency — it doesn't replace answering a real question about the job, or the conversation that actually closes it. The goal isn't to take you out of the sale. It's to make sure the sale is still live by the time you're back in it.