Don't forget we are trying to replicate BIR dishes, so when a chef makes his/her dish they don't use teaspoons and tablespoons as a measurement its by eye, as many people on this site have stated before.
So really if you take on board that an average serving of curry is 300ml (this is what i use) and the chef puts in 3 ladles there's your answer, if the chef adds 2 ladles and YOU don't think the dish looks "wet" enough add another half a ladle and take notes, use google to look up dishes and see what they should look like.
For example i didn't know what a Roshni looks like, there are descriptions and photos to look up, its not going to be laid on a plate for you, you have to do a bit of research for each dish, well i do anyway, i look up where its from, what region, and where its eaten the most and then i read descriptions.
Some people may have a different amount of curry served to them from their local T/A, but that's the region thing again.
Anyway hope that helped a little.