It may make sense to have several build zones, say one for each major project, or using a "pristine" one for testing of your packaged builds when you think your project is nearing the finish line. In these cases it is recommended to set up one build zone properly, take its datasets' ZFS snapshot, and then clone it and reconfigure the clones as new local zones – this would guarantee that the zones are identical and save you some disk space and internet traffic.
In particular, local zones can be used along with multiple cloned workspaces (see Working on several bugs at once) for preconfigured compilation of the same project code-base with different supported compiler suites (SunStudio, GCC, whatever comes next?)
The Distribution Constructor (the software that produces the final ISO Image) does not work inside a local zone.
Note that there are other ways to clone zones, and unlike the hacks in previous paragraph they are "supported", but those would usually clone a zone's current state instead of using a "golden image" as you can do with the snapshots above. Alternately, you can hold the unused preconfigured "dummy" zone as a golden image, and properly clone it with the supported system tools and methods (making the first clone now for your actual development work).
for preconfigured compilation of the same project code-base with different supported compiler suites,