Does anyone do indidividual marketing rather than mass marketing?

I'm in the software niche, but since now I'm in a larger city, have recently took up an interest in offline marketing.
I keep reading a lot about people mailing like 100 clients with a generic offer. There hasn't been a single mention about individual marketing in a while. Instead of direct mailing a whole group of businesses, I have researched a successful dentist with a 2.6/5 star rating on Google and a poor website. This dentist also participates in PPC marketing. I think rather than direct mailing all of the dentists, I'll build up a nice customized package of solutions for this dentist, including making the website better, with pictures of a mock-up, and what I can do with his Google reviews, and what they currently look like. Bind it in a nice package and walk into the dentistry myself and drop it off.

So does anyone here do individual marketing, or does everyone only do mass marketing? I think I can squeeze a lot of money out of 1 dentist if I offer an array of services and bundle it.

What you have to weigh up is the amount of effort, time an cost you are going to put in to get
this one client against the potential rewards.
Although I do mass mail to get in some bread and butter clients. I receive a better response to an individual critique
of a potential clients online position.
When a potential client has seen that you have really done your homework they tend to be more receptive to
your proposals.

How many times have you been told what you need to do before being asked what you want to achieve?

I used to sell an insurance pack with individual marketing method. It is tiring, time consuming, and quickly drain my mental strength. Collect a lot of potential customer address and get ready for mental fight. Prepare your best weapon: lips service plan and a lot of smile.

Just be helpful, be patient, and you'll be okay.