Factory reset for every Cyanogenmod Update? I plan to install Cyanogenmod on my new Android phone. For this first install, I've to do a factory reset - what's no problem on a factory new phone.
But do I have to perform this factory reset on every minor and major update of the mod in the next month and years - and loosing all my app settings, logins, game highscores etc. again and again?
Or does the Cyanogenmod update behave like a normal Android update (just a little bit downloading, rebooting and continue with all apps and settings as before)?
You can either update manually or using installer instructions

Quoting from Cyanogenmod official site updating related to manual
Updates


  If you are doing a major update (such as from CM 7 to CM 10) or wish to clear the device's data partion, select Clear data partition or Factory Reset (depending on the recovery menu you are using)


Again from release versioning


  CyanogenMod 9 - 10.2 build tags-
  CyanogenMod 9 through 10.2 were qualified with tags: Experimental, Nightly, Release Candidate, and Stable. The Snapshot tag was added with the introduction of M builds in CyanogenMod 10.2. These tags were meant to indicate a build's suitability for general use.
  
  Nightly: usually generated every 24 hours, experimental, newest features, unstable
  Experimental: testing version requested by device maintainers to evaluate specific changes
  M Snapshot: milestone snapshot, more stable than a nightly but potentially some issues
  Release Candidate: last builds before stable release, few minor issues, mostly stable, and safe for daily use
  Stable: most stable version available, all or nearly all issues resolved


Nightlies are not recommended unless you can handle issues arising out of it 


  These ROMs are largely untested, and as advised by CyanogenMod, not meant for use for an average user. 


To answer your question now, avoid nightly/ experimental/ snapshot  builds, install only stable builds and update as recommended by CM installer or manually as highlighted.

Generally minor updates and nightly builds do not need factory reset

This is about official builds. If you are sourcing your build from other developer forums follow their instructions