A quiet week, and you are paying again for new leads.
Meanwhile the people who already paid you once are quietly forgetting you exist.
You bought those customers the hard way. Doing nothing means buying them all over again.
I keep track of everybody you have worked for and what you did for them.
When it is actually useful to get back in touch, I do. A boiler that is due its service. A job you quoted for last year that never went ahead.
Not once a month because a calendar said so. That is what makes it feel like spam, and it is why most of this is done badly.
The people on your list already chose you once. That is a warmer start than any advert you could pay for.
If somebody would rather not hear from you, they hear from me once and never again. That is their right and it is also good manners.
You are not renting software. You are putting somebody on the job who does one thing properly and does it every time.