  Reducing the average resource consumption is the central quest in
discriminating non-orthogonal quantum states for a fixed admissible error rate
$\varepsilon$. The globally optimal fixed local projective measurement (GOFL)
for this task is found to be different from that for previous minimum-error
discrimination tasks [PRL 118, 030502 (2017)]. To achieve the ultimate minimum
average consumption, here we develop a general globally optimal adaptive
strategy (GOA) by subtly using the updated posterior probability, which works
under any error rate requirement and any one-way measurement restrictions, and
can be solved by a convergent iterative relation. First, under the local
measurement restrictions, our GOA is solved to serve as the local bound, which
saves 16.6 copies (24%) compared with the previously best GOFL. When the more
powerful two-copy collective measurements are allowed, our GOA is
experimentally demonstrated to beat the local bound by 3.9 copies (6.0%). By
exploiting both adaptivity and collective measurements, our work marks an
important step towards minimum-consumption quantum state discrimination.
