since the first 737(-100) in 1968 (?) that thing has only gotten bigger but never seen any real development or improvement. that leaves me on the B738W with speed brakes that are (almost) completely useless at speeds 250 and less. on the other hand i -could- use flaps 5 up to 250kts (see placard next to lever).
i don't know if the FCTM forbids using flaps 1/5 for drag (i doubt it) but i won't drop the gear 20NM out if i can help it.
(YES, i know extending flaps at speed close to max placard will sooner or later f*ck the fairings and my company programmed the acars to send a report if i do so above 230 IAS
)