It’s a bizarre approach, because it’s not like they are overloaded, and have people lining up wanting Bible studies. From what I gather, in the 1970s, leading up to 1975, there was actually a period when JWs had so many Bible studies it probably made sense to prioritise. But now? I think they’re deluding themselves.
Then again, it’s probably not about making the best rational use of time. It’s more about giving JWs a sense of self importance about their ministry. Plus the whole organisation works on the principle of “do more or you are not good enough”, so projecting this attitude toward people who are only at the early stages of entering the movement is a natural extension I suppose.