Back in the 80s we used purchased modules approximately 2/3 of the time but, significantly, even our home-brewed adventures slavishly followed the TSR module format -- they'd have about the same size of maps and number of encounters, the same types of challenges, the same sorts of backstories and plots, the rooms/encounters would be written up in "module" format including statblocks and read-aloud boxed text, and we'd give them names and letter-codes (I remember at least one where I even included optional "tournament scoring" like the A and C series). So even when we were playing home-brewed stuff we still played in the episodic "module-style" and never in the more freeform/open-ended campaign mode of OD&D or a lot of the advice in the DMG. Between-adventure downtime and large-scale wilderness travel were always handled abstractly -- when we finished one advaneture we'd mark off an appropriate amount of in-between time (usually a couple months), do our bookkeeping (training & upkeep costs, buy new equipment, hire new followers, etc.), and skip ahead to the canned intro of the next adventure.
EDIT: FWIW, my current AD&D group has been together for almost exactly 3 years meeting approximately every other week (but with lots of missed sessions), and in that time it's all been home-brewed material except for a lone 2 session "break" around last Xmas when I ran a one-off module separate from the regular campaign -- so the total there is less than 5%. However, even so we're still playing in more or less "module-style" in that we're playing discrete "adventures" with beginnings, middles, and endings and the downtime in-between glossed over rather than an organic freeform no-visible-seamlines sort of campaign.