A homeowner calls, describes the problem, asks "about how much," and it's tempting to just answer. It feels responsive. It also skips every step that would have caught the thing that actually determines the price — the access, the age of the existing work, the code requirement that wasn't visible over the phone.
What a verbal number actually costs you
Once a number is said out loud, it's the number the client remembers — even if it was framed as "roughly" or "depends." Coming in higher after an on-site look reads as a bait-and-switch even when it isn't one, and that conversation costs more goodwill than the extra five minutes of a proper walkthrough ever would have.
A better default
Give a range grounded in the most common version of the job, not a single number: "Jobs like this typically run $X to $Y — I'll get you an exact price after I see it in person." It answers the question honestly without committing to a figure that hasn't been priced.
Where this actually saves time
A written quote, even a same-day one, does something a phone call can't: it puts line items, terms, and a deposit request in front of the client in a format they can approve without a follow-up call. Fewer verbal quotes, more same-day written ones, is usually a net time saver, not a cost.