How long should a run be?

     There was a show a few weeks ago that I had seen, which had odd faults that I thought would sort themselves as the season went on, however they didn’t, and the show was later described as ‘dire’. Recently a couple whose opinion I respect told me, that another comedy that I had really enjoyed and highly recommended was awful.  This presentation was by a well-established and respected company. On the night that I saw this play it was at it’s best for timing, pace, interaction, visuals etc, yet according to my friends, with their performance nothing worked. Even the story was hard to follow, and the cast appeared to be floundering - there was certainly no magic there.
      Every company has the odd bad performance, but what I am wondering is, with community theatre especially, does ennui set in towards the final show?
      In the UK the pantomime season runs for up to three months, even the Curtin pantomimes used to run for 32 shows, by the end of which the cast were exhausted – now it is around only 12 shows. Recently ‘King Lear’ was on a long national tour, but the cast still kept up the quality. Should the audience, or the producer, be prepared to accept large variations in the nightly standard of amateur theatre?
       Because a play or its writer is well known, or the show has a famous TV background, does this mean that the number of performances should be increased to meet public demand? Should the season be set at what the cast are capable of handling? Or are some runs simply too long?