Question for Bob Gardner - Multiengine bank angle

I just finished reading the Jeppesen "flight discovery" series for
their Multiengine manual, and just started reading the ASA's The
Complete Multiengine pilot. I noticed in their book that they
mentioned several times that, for best performance, you don't need 5
degrees of bank that planes are tested at. It stresses to use less,
such as 2-3 deg. depending on the plane. I noticed in your book (pg.
1-5) it says "at least 5 degrees"...which is correct? I'd have to
check the Jeppesen one again, but I think they tested climb rates with
different bank angles to figure the best one.