General question about compiling and installing with GARNOME

["J. Gardner Biggs" <gardnerbiggs houston rr com>]

Ok, sorry if this is a bit basic.

I just ran a $ tla update on my garnome--kenny--2.7 tree and received
patches 5 to 8.  cool

My question is this: if I do a $ make paranoid-install on the /desktop
and all builds and installs with out any major problems, and next week I
update the source tree with another $ tla update, can I just run another
$ make paranoid-install to get GARNOME to only build/install the
packages that have changed?  Or do I need to do a $ make clean and start
all over from scratch?

I ask this since it takes around 5-6 hours to compile desktop on this
computer.

Thanks for your help and patience.