"Whether you're a star, a sideman, a session player, or a serious student, the Lab Series works"
This advertisement from early 1979 illustrates the above claim with examples of each. The Star is Ronnie Montrose, who had previously appeared in a Lab Series advert for the L5 (here) in 1978, but is shown here on stage with the Lab Series L11.
The sideman was Joe Turner - bass player with BB King, who would himself go on to appear in a Lab Series advert in 1981. Turner uses the 200w 2x15 Lab Series L4.
The session player, although not named here, is Muscle Shoals legend Dave Hood; playing his long scale Alembic series 1 through the 100w 1x15" Lab Series L2 bass amp.
The serious student role is filled by a bunch of Guitar Institute of Technology players gathered around a single Lab Series L5. There are an awful lot of Gibsons on display!