You said you learned from experience to never give estimates in person. How is this possible? You would need to take precise measurements for the job in order to give an accurate estimate. For lawn service, I do not need to give estimates in person because I price my lawns +$5 (from drop-gate minimum) corresponding with +1/4 acre intervals. If the people only have a ballpark of their yard size/trimming requirements I give them a general idea of the price and give them a regular weekly rate after their first cut which I estimate and bill them for after the fact. But for landscaping I can see only rare instances where in-person estimates wouldn't be needed. Maybe hourly rate spring cleanups or mulching with zero prep work and an exact amount of mulch requested by the customer.