I believe ANY small kitesize has been used, even 1m2 kites, just to try on big boards.
But around here, 3 and 4m2 is "small" kites, that some has.
And they are standard small kitesize by some brands.
A 5m2 kite is the typical small kite all brands delivers, but very often used, and can also be too big around here occasionally, and at other spots like South Africa, where it is often too big
I simply HATE small kites without depower - almost useless IMO, for waveriding (which I think is what most are using these sizes for).
Because, a small kite is used in windspeeds, where you need a huge amount of more depower than t.ex with a medium kitesize (a 7m2).
When you ride Down The Line, you DONT want the kite to pull you off your line - which is exactly what it does if it has the same camber as bigger kites
Freeriders or freestylers might like powerful small kites, because it is easier, and they dont need the powerdump like in waveriding.
So with small kites it is really difficult to please everybody
But a must with this size if you are riding waves, where a 6m2 kite is NOT a small kite
I've ridden a 3m2 kite for freeride/freestyle years ago, but kites were more powerfull back then (and useless for waveriding)
You can ride with any small kitesize, if sufficient wind.
The problem is, that it will never be any good, as when winds get up to speeds where 3-4m2 kites are too big (and even there IMO), the water surface is spoiled, chop on the waves most often, and for flat water it is, hmmmm, not really flat water - and it will be waterspray also, above the surface, so really really unpleasant to ride
Most are just doing it to be able to SAY that they were out in this and that
Or because they have never done it in these winds before.
Not because it is any good...
Peter