Broadly speaking, the accuracy will decrease the further back in time you consider. This is primarily because the completeness of the geologic record as preserved in rocks decreases as a function of age (though not necessarily linearly), but also because uncertainties and/or errors related to various assumptions that are made to construct paleogeographic maps also increase as a function of age. Thus, the level of accuracy is pretty different for a paleogeographic map of the last glacial maximum (~24,000 years ago) compared to the early Cambrian (~530,000,000 years ago) and so on, but not necessarily easily quantifiable.

Within a given map, there will also likely be portions that are much more certain than others. It's worth considering the primary datasets we use to construct paleogeographic maps and what each dataset provides in terms of information. The base for virtually all paleogeographic maps are plate tectonic reconstructions, i.e., at a given time, where individual tectonic plates were, what shape they approximately were, where were their continental and oceanic components were, and what rate and direction they were moving. A variety of data informs these reconstructions, including paleomagnetism (which allows us to reconstruct paleolatitude for locations at a given time), a variety of geophysical data (it's increasingly common to use seismic tomography to reconstruct subducted slabs and "undo" subduction to aid in reconstructing ocean basins), and other geodetic data for more recent reconstructions (for recent reconstructions, the current long-term average plate rates can be extrapolated backwards reliably for 10s of million years). In addition to tectonic reconstructions, the type rocks of a given age in a location can also provide context, e.g., rocks that are diagnostic of near shore depositional environments provide context that at the time those rocks were deposited, the coastline was near that location, etc. What this means is that for most paleogeographic maps (at least within the Phanerozoic, and into portions of the Proterozoic) the broad locations of continents and their first order shapes will be broadly correct and probably in roughly the right location (in the sense of latitude and longitude). In certain places on these continents, there might be higher levels of certainty of the location of the coasts and things like major rivers based on the rocks that are preserved. Similarly, large mountain chains will be approximately in the right place, but many of the details of them (e.g., their exact widths, heights, etc) will be only relatively constrained. Lots of fine scale details would not be preserved, some of which might certainly impact the utility of maps for navigation, so things like smaller rivers (and even some large rivers) and small to moderate sized islands (so things the size of Hawaii, etc) would generally not be preserved so a paleogeographic map would not include it, and again, more so the further back you go.

Finally, when considering paleogeographic maps, it's also important to realize that there is a fair amount of artistic license taken in many cases. A good paleogeographic map will use as much of the available data to constrain as much of the paleogeography as possible, but there will still be a lot of unknowns so choices have to be made. Different people making paleogeographic maps take different strategies for how to make some of these choices. You can compare some commonly used sets of global reconstructions, e.g., those from Christopher Scotese and those from Ron Blakey, to get a sense of the variability. Without a doubt, Blakey's maps are much more aesthetically pleasing and he does a huge amount of work to make sure they're as accurate as they can be, but he also takes a lot more license to make things always look complete and like "real" landscapes (even when that completeness is effectively made up). In comparison, if you look at especially old time slices in Scotese's maps, they look more like blobs on the globe, which is not as pretty, but more accurate in terms of the level of certainty we have with respect to the actual paleogeography.

In short, the level of accuracy will broadly scale with how far back in time the period that is being reconstructed, with paleogeographic maps reconstructing periods further back in time being less accurate than more recent times. Within a time slice, some features will be much more certain than others where as some features will be effectively made up depending on the available data for that time period (and the preceding and following time periods). All of this means that we can't really quantify the accuracy of these maps (and we can't ground truth them either), but depending on the level of "navigation" you had in mind and the time period in question, they could be used to navigate to some degree. Broadly, if you trying to get from one major landmass to another by boat, most all of them would probably be good enough (at least within the last few hundred million years). If you were trying to navigate over land, there would probably be a lot of fine scale details that you would have no idea existed based on the map. Further back in time, even navigation by sea would become a bit more tricky as the probability of a semi-large island chain being in your way (that's not on the map, because it was not preserved in the geologic record) goes up.