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)?
Generally speaking you don't have to perform a factory reset when downloading a newer build. The flashable zip should perform all wipes by itself if it is necessary (only certain partitions are affected - your data should be safe). Many developers include an OTA(Over-The-Air)Update Application so you can comfortably download and install the new build with 1-3 clicks. It depends on which device and which custom rom you are using.
In most cases you only have to perform a factory reset
- when you're performing a fresh installation of CM
- the android version changes(factory reset may not be needed but it is adviced most of the times)
- when something goes wrong :)
The best thing to do is to make regular backups and save them on your computer - this way you won't loose much.
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