This topic has been beat to death many times over. A search will show any opinion you wish to choose.
In competition: benchrest, across-the-course, and long range, moly was quite popular 10 years ago. There are very few using it now.
About every 5 years or so there is a 'new miracle' barrel treatment. Moly has lasted much longer than most so probably does have some benefits in some circumstances.
To answer your question, yes moly does require many shots with moly coated bullets to give good groups and pre-treating can reduce the number of shots needed.
Jack