Hello and welcome to the LEF

No, the engine should not use all of the valve stem oil in 4 hours. There is no seals on the valve stems, they rely on correct fit but India screws up several things that affect how much oil is consumed.
First thing is that on most, but not all India guides they decided it would be a good idea to drill a small hole in the side of the guides to let the oil run to the stem. If your guides are drilled then you cannot stop the oil usage without dissasembly and plugging them. I use a piece of lead shot with a tight fit.
Second thing is a loose fit of the valves in the guides. Original valve stems were 7/16" Some India valves are 7/16, some are 11mm. All of the guides are 7/16" if 11mm valves are installed in 7/16 guides(common) there is way too much cearance and oil consumption will be high.
Third thing is India will put a huge chamfer on top of the guides to act as a funnel, another bad move. I machine them flat and lightly deburr.
All of the fixes for oil consumption require head removal and machine work. Very little oil is needed up there. The bulk of the engines that go through my little operation have never been oiled up top or seldom at best and they don't seem to suffer for it.
Last thing is the black goop in exhaust is not always from oil, it can also be from bad injector or bad injector timing and what appears to be oil is just unburned fuel and carbon mix. This is more of a problem with cold and lightly loaded engines than hot and heavily loaded.
When everything is done right up top you should see very little oil usage up top in an 8 hour run.