I have two home tetrads: one in VC35 and one in VC44. Both are pretty ordinary but have the advantage of me being able to repeatedly poke around in all sorts of different habitats, picking up small populations of varied bryophyte species. Actually, the Dingestow tetrad SO40P (half way between Raglan and Monmouth) is rather non-ordinary because it includes a large Victorian garden, lots of setaside and arable, and a wooded ridge with base-rich springs and planted conifers, but there are any number of equally diverse tetrads in eastern Monmouthshire.
Additions keep coming, both arriving de novo and just being discovered afresh. Encalypta streptocarpa seems to be a newish arrival on an asbestos roof, whereas lumps of tufa in the garden produced Tortula marginata and Seligeria donniana of assumed long-standing this summer.
The tetrad list for SO40P (Dingestow) now stands at 217 taxa, with highlights such as Acaulon muticum, Amblystegium humile, Anthoceros agrestis, Aulacomnium palustre, Bryum caespiticium, Chiloscyphus pallescens, Colura calyptrifolia, Drepanocladus polygamus, Ephemerum sessile, Eurhynchium schleicheri, Hennediella stanfordensis, Leiocolea turbinata, Leucodon sciuroides, Orthotrichum pallens, Phaeoceros carolinianus, Platygyrium repens, Pylaisia polyantha, 3 spp of Racomitrium, Sematophyllum substrumulosum, Syntrichia virescens, Weissia longifolia, W. multicapsularis and W. rutilans.
The Cnwc y Llwyn tetrad (SN53A) is lagging behind a bit at 181 taxa.
The big question is how we can expect to get genuine complete tetrad coverage in any county, when a good day out in a tetrad in either SN53 or SO40 would produce 80 to 100 species, the true scores are more than double that, and there is little or no chance of repeated visits to anywhere other than our 'home' squares.