There are several things we can improve/clean up.

• set up log rotation
• don't reimport images that are already present (Modification to MW scripts needed)
• don't export all revisions/pages but only those from the past few days. (Modification to MW scripts needed, standalone script for handling deletions/moves needed, see T128548)
• find out why the log is flooded with 'XMLReader::open(): Unable to open source data" for image imports: T206013
• don't rebuildImages ever, just let importDump take care of it

There are likely other things too but this will do. I'm looking into the 'Unable to open source data' error message. The rest are up for grabs for now.