Can NLog be configured to automatically prune/trim a log file after it reaches a certain file size?
I think the closest you will achieve will be to use the archiveAboveSize attribute to get NLog to archive the log file when it reaches a certain size. By combining this with the maxArchiveFiles attribute, you can keep the number of archived files to a minimum (although I think you will always need one archived file otherwise when the current log file gets archived and replaced with a new one, the now-archived file will be deleted and you will lose all of the logging in it).
There is an example in the documentation.