Indeed, it all depends on the individuals concerned. My grandfather did apparently, set about teaching his children to read and working on their spelling when they were quite small (he seems to have been a serious-minded man and particularly concerned that they should have a good education - he had left school at 13 himself). My father also remembers being taken along with him on odd visits before he went to school (as I do with my father) - presumably to give his mother a break as much as anything.
But in any case, back in the 1920s, when Rupprecht was producing his second family, men weren't expected to be all that interested in infants. If Rupprecht was a good provider, provided discipline where needed and set them an example, that was all that was needed.
Interestingly, George V (29 when his eldest child was born) seems to have been quite the hands-on father when his children were infants (giving them baths and the like), but distance developed when they got older.
Ann