If you're doing something right, and it's making an impact, your competitors will pick up on it. If your competitors start changing their own strategies and tactics, and if it seems like they might be doing this in response to your campaign, it's worth looking into. Identify your main competitors and analyse how their own email messaging has changed (if at all) during your campaign.
Not only was this initial email great, but his response to my answers was even better: Within a few days of responding to the questionnaire, I received a long and detailed personal email from Matt thanking me for filling out the questionnaire and offering a ton of helpful advice and links to resources specifically catered to my answers. I was very impressed by his business acumen, communication skills, and obvious dedication to his readers.
As long as you are keeping track of your client’s most recent appointment times, this kind of automated reminder email is quite easy to set up. Use a custom date field to record when their last appointment time was, then set up the email to be sent 3 months later (or whatever your recurring schedule is) to remind them that they are due for their next appointment.
That isn’t to say that sales-y promotions couldn’t ever create results—as marketing “gurus” have proved. The results just aren’t as good as they could be. Take the biggest gurus’ results—the ones they boast about—and calculate their conversion rates. Often their marketing is comparatively ineffective. They just have massive volume, so the sales numbers are impressive.