I made some plots for my own observing projects, and since they provided me with more information than I initially expected, I give here a link in order they are interesting for someone else: https://franta-d.raj...iven_magnitude/
(try this link https://www.rajce.net/f1390563728 if the previous link does not work). Please find a brief description of the plots in the link. I apologise to observers from the southern hemisphere, because the maps aim mainly at the northern sky.
The maps showed me several interesting features: when we have a telescope which sees one 1 mag further, it shows 3x more galaxies. This trend continues from 10 mag up to 14.5 mag, and then the increment is smaller - but this is likely because of the fact that the catalogue is incomplete for fainter objects. Another feature is that Virgo cluster, which is a conspicuous overdensity for mag < 13 galaxies, it becomes only one of many galactic clusterings when we exceed mag > 14.5. I am also surprised how many galaxy clusters are there already for mag ~ 15. Although I have seen many overdensities in galaxies in Uranometria, I expected that they are mainly beyond reach of my telescope (with perhaps the exceptioon of the brightest galaxy, but seeing only one galaxy does not seem to be that attractive). We can also easily see the substructure of the Virgo cluster (mainly around M 61, M 98 and M 60) on the zoom-in plots (files Vir_et_Com). It is also clear how the Milky Way obstructs our view outside.
Since my humble 250mm skywatcher dobsonian reaches to 15-15.5 mag on galaxies under excellent skyes, I am tempted to try more of these objects.