Gym model. Gyms routinely sign up more people than they have capacity for, knowing that most people will go for the first few weeks, and then stop.

I bet there's a normal distribution for the work that sees new clients creating 90% of the workload, fading down towards zero as they age.

Agencies (even of one) also get economies of scale that gyms don't. You have templates, pre-built components, domain specific knowledge of how to handle common problems, etc.

You also have subcontractors that you can farm stuff out to or help when volume surges. I think the “of one” is likely not always true.

From what I've seen, it's pretty universal for contracts to individual freelancers like this to have an explicit "no subs" clause or at least require prior approval of specific subcontractors. I guess you could lie, or try to negotiate your way out of it in some cases... but I wouldn't count on that at scale.

Gyms have machines, and personal trainers have basic starter programs.

But who pays $2500/month for nothing?

Some, but not many will pay that for nothing. But many pay $2500/month for peace of mind.

I've had contracts like that renew for years with little work most months because a client just wanted to know I was incentivised to be available when they suddenly needed me.

I don't know how DesignJoy works. I can say that a common model in this circumstance is the person is a salesperson who outsources the rest of the operation to a network of subcontractors, including project management, AE, and fulfillment.

Sometimes this is called a "network agency".

I dug a bit deeper. Looks like it's truly a "agency of one" in that he doesn't outsource his work. Rather, the customers are given access to a queue (that they can prioritize) where only one item in the queue is actively being worked on at a time.

Right. But you likely end up with most of these clients being pretty dormant and a few, or the new ones, being needy. If any given one is too needy then you cut them.

In practice many companies have a similar model they just dont say it. I mean technically as a dev I'm going to make as many revisions to my code as is requested and I get paid the same amount at the end of the month. My team just knows if its 500 revisions then there are probably some issues with the asks or my code.

Compared to a day rate contractor, $2499/mo is very little, so if you have bitty requests rather than a need for a full time staff member, your "unlimited" could easily be not very much, but still better than finding someone to do your on and off work.

I still find it very hard to believe that this guy is handling everything by himself.

Sole employee![0]

[0] (but sub-contracts work out extensively)

Just about guarantee that's the situation.