The 200 to 300 figure isn't a rule, it's a rough floor for getting a readable response rate. Direct mail to owners of visibly distressed property tends to come back in the low single digits per mailing, so a list of 40 can easily produce zero replies while your route is perfectly fine. At 250 addresses, zero replies actually tells you something.
A few terms so the numbers line up. Your "list" is the addresses you logged. "Skip tracing" is paying a service to match an address to the owner's name, mailing address and phone, usually somewhere around 10 to 25 cents a record. Mail itself runs roughly 50 cents to a dollar per piece depending on format. So 250 addresses, skip traced and mailed once, is maybe $200 to $300. That's your real entry cost, and it's why the size of the list matters to your wallet.
The part that trips people up more than list size is repetition. Most responses to distressed-owner mail come on the third, fourth or fifth touch, not the first. If you budget one mailing to 250 people you've bought one touch. Many drivers would rather mail 100 addresses six times than 600 addresses once.
One more thing worth building in now while your list is small: log the date you saw the property and a note on what the distress was. Six months later the yard may be cut and the house listed, and you'll want to know that your signal was real.
