There are several maintenance scripts waiting to be run on many wikis since years ago: https://bugzilla.wikimedia.org/showdependencytree.cgi?id=29782&hide_reso... The biggest offenders are: * https://bugzilla.wikimedia.org/show_bug.cgi?id=16112 which breaks tons of special pages; * https://bugzilla.wikimedia.org/show_bug.cgi?id=33253 which makes the article count on those wikis completely broken after the count method change.
The fact that we could/should find a perfect and permanent solution for those problems doesn't mean that we shouldn't improve the situation given that we can. The fact that we can't run them every month as we once did doesn't mean that we shouldn't run them say every 5 years (which would be an improvement) or after big changes (such as the count method). Even the longest scripts of that sort, when run by pdhanda some months ago, took only some days for all wikis and didn't do any damage.
Nemo