For example, You want to install pidgin from source code. The better place is ".../src/" or ".../local" ?
nether but maybe /usr/local
it REALLY depends on your operating system and HOW !!! YOU !!! set it up
i build a LOT of programs but i keep them OUT!!!! of the default OS directory tree
i use a second tree for all the programs i build
( this way if i FUBAR the OS i can reinstall the os EASILY )
so is set my build path to "/DATA/SUSE "
this then causes "make install" to install it to
some people like where Libreoffice installs
some LIKE to use the "local"
this dates back to server / terminal of the 70's ,80's and early 90's
where the local directory WAS on your desk and "/" was on a server someplace
use what you want
but you might WANT to stay consistent and use that ALL the time