It is interesting to note that they give the same site to prefix allocation chart as their website which is outlined below:
|Number of Sites||Prefix Block Size|
|3,072 - 49,152||/32|
You can find the details for how this actually works on the ARIN website.
I would expect most enterprises to fit in the /40 to /36 category as ARIN's definition of a site is relatively broad. They did this intentionally and as you can see in the definitions that follow, you can argue your single work from home user would classify as a site.
From ARIN's website:
"22.214.171.124.1. Standard sites
A site is a discrete location that is part of an organization’s network. A campus with multiple buildings may be considered as one or multiple sites, based on the implementation of its network infrastructure. For a campus to be considered as multiple sites, reasonable technical documentation must be submitted describing how the network infrastructure is implemented in a manner equivalent to multiple sites.
An organization may request up to a /48 for each site in its network, and any sites that will be operational within 12 months.
126.96.36.199.2. Extra-large sites
In rare cases, an organization may request more than a /48 for an extra-large site which requires more than 16,384 /64 subnets. In such a case, a detailed subnet plan must be submitted for each extra-large site in an organization’s network. An extra-large site qualifies for the next larger prefix when the total subnet utilization exceeds 25%. Each extra-large site will be counted as an equivalent number of /48 standard sites."
Remember, if you run labs, dev and test networks that might have to simulate an entire site then you need to include each of those as sites and not as a single /64 subnet in your design and request to ARIN. Otherwise you will not have enough address space to build out those test environments that you might require and you will have to go back to request address space.