I am having huge difficulties with updating glib2. I use 'make update'.
This causes many, many packages to rebuild. It looks like first they
are build and installed, and only as a final step all packages are
cleaned. Why is the 'make clean' not done just after an install? It
will save a lot of disk space.

Now, the sequence seems to be:
build W
build X
build Y
install Y
build Z
install Z
install X
install W
clean W, X, Y Z

Why not:
build W
build X
build Y
install Y
clean Y
build Z
install Z
clean Z
install X
clean X
install W
clean W

	rvdp