Changing the Asset Category

Hi,

 I had changed the Asset Category in few previously loaded assets thru from front end navigation of :: Asset Workbench>>Assets>>Open>> Changed the Category to the new one

 Let me know by doing this, will  the asset inherit the Depreciation Method also of the new category automatically or do I have to change it manually by going to Assets>>Books form?

 In my case it is observed that in some cases the Method was changed as per the new category automatically  and in some it remained as per old category ??

 

Rgds

Dev