Ours are only labelled on a map. No plot signs!
Our allotment officer seems incapable of identifying the correct plot number/holder without the plots being individually numbered. People whose plots were spotless receiving non-cultivaton letters, stopped being amusing after a while
We have the same here
The plots were originally full size, then half size (and renumbered) then a mix of both and the numbers do not correspond to the map/plan
I do like the idea of standardised numbering though... the fascia boards sound lovely, and wheelie bin numbers could look good too.
Ours is varnished wood with the digits routed out on it, so it can't fade. Screwed to the gate post and looks very smart.
As for boundaries, we are expected to fence our own plots, so if you get one adjoining others with no fence, it can feel a little unfair. The plots are all 10m wide though (differing lengths) so measuring before erecting a fence is quite usual. Fences are rabbit proof wire on wooden posts, with a suitable gate. Some plot holders have added upright pallets painted in various colours, which look very bright and cheerful, other have employed heris fencing which looks hideous