[yocto] rebuilds -- when to do what??

[jfabernathy]

Over the past 6 months, I've learned a lot about what I should do to 
work with Yocto successfully, However, the area of biggest confusion for 
me is what to do when I want to rebuild something.

I generally work from Master repository and when I see significant 
changes while doing git pull, I try to rebuild one of my projects.  I've 
tried a lot of the methods:

1.  just bitbake again.
2.  bitbake -c cleanall or -c cleansstate core-image-sato
3.  If I know a recipe has changed, I'll bitbake -c cleansstate "recipe 
name"

Most of the time something fails.  Researching what, is an impossibility 
to me and much quicker to just delete the build directory and redo it.

Is there a good "how to" rebuild?  Or is it the best use of time to just 
tell users to blow away the build dir. and restart, saving the old 
local.conf and bblayer.conf?

Jim A