Well, and unless I am mistaken, they still route the larger subnets to your interface rather than to your machine? There it nothing wrong with testing stuff with "small" subnets, even if it may be a bit pointless, but my point is that a setup that provides you with a single address just has a structure that cannot really easily be changed in a sane way into a setup that provides you with larger subnets.
A sane setup should use a transfer net on your interface, and should route your actual address space to your gateway address on that transfer net - otherwise you'll need ugly hacks such as proxy-NDP in order to be able to route addresses for sub-allocations. This flat setup without a transfer net was invented for IPv4 when IPv4 addresses became scarce, so it was a necessary evil, but it's a stupid setup that causes nothing but pain when you have billions of /64s available.
That is the reason why I don't understand why anyone would even test with single-address allocations.
A sane setup should use a transfer net on your interface, and should route your actual address space to your gateway address on that transfer net - otherwise you'll need ugly hacks such as proxy-NDP in order to be able to route addresses for sub-allocations. This flat setup without a transfer net was invented for IPv4 when IPv4 addresses became scarce, so it was a necessary evil, but it's a stupid setup that causes nothing but pain when you have billions of /64s available.
That is the reason why I don't understand why anyone would even test with single-address allocations.