Initial estimate is for investigation only.
Richard has been working on this and has reduced the footprint of a number of key areas, there has also been work contributed by the community to address issues around rm_work.
Compared to 1.3 size of tmp dir decreased from 30G to 27G for a core-image-sato build. (7.6G to 6.9 with rm_work enabled). Setting to Verified.
This is covered by the following test case: https://bugzilla.yoctoproject.org/tr_show_case.cgi?case_id=744