A number of wills are in the indexes (I'm referring to the filmed indexes, not Brian's) which do not appear on either the MM films or on the LDS films available through their Family History Centres. In a couple of cases the MM allowed the original documents to be copied when they couldn't be found on their films. I later found one of the wills on an Epis film when it was in the index as Arch. So finding a will is often not straight forward, and I would estimate a much longer "searching" time than Frances has given, for at least a third of them - especially Epis ones. This is why MM staff stopped their wills photocopying service. It is a lot to ask someone else to search for them.

I imagine Brian compiled his index from the official indexes on film, and then compared the dates to the LDS film numbers. This would have taken an enormous amount of time (most were hand-written), and if he had checked each wills film as well he would still be doing it, at the expense of all the other indexes he has compiled.

Frances, if you find missing entries you could let him know, as I have done, and he will add them to the index.
I'm not sure what you mean by the indicated film number is not always accurate, because I was under the impression that the film numbering at the MM differs to the numbering on LDS films at FHCs?

Sue