The final Three-Strip patent (1955) had all three colors with nearly
the same transmission factor.

After sputtering about eighteen layers of metal in microscopic
thicknesses, Technicolor techs got just about a square wave transfer
function centered on the three primary colors of interest, and about
the same amount of attenuation on all three colors.

However, by that time, Three-Strip already had an effective ASA
advantage over Eastmancolor, but so much product had been diverted to
'Scope (for which Three-Strip was impractical) and wide-gage, that it
was overdue to put Three-Strip out of its misery.

http://www.groupsrv.com/movie/about106246-0-asc-15.html

There were only 50 titles completed in Three-Strip in 1955, and that
was all she wrote.

One-half of the Three-Strip cameras were almost immediately divered to
VistaVision.

For a process which lasted two decades and a half (1932 to 1955), that
was a pretty good run.