My PA28-181 has an adjustable rudder trim so I do tend to tweak it while in the cruise (and if doing a steady climb or descent).
Years ago my brother was in a Robin Aiglon group - it had two small plain aluminium taps one riveted on the port aileron and one on the rudder - these could be tweaked with pliers, once set they were left for years, put the bubble in the middle in the cruise.
Not too sure if they were 'standard' for the Aiglon or someone's unapproved tweak but they did work.