IIR by the time AD&D 1st Edition Dungeon Master's Guide was published, there were already a bunch of blooming competing systems, with different dynamics between explicit and implicit, not to mention the combat systems. Those alternates include the Arduin Grimoires for example! Not everyone read or stuck with AD&D 1st Edition Dungeon Master's Guide but some did.
There was to me (it seemed at the time, given I was in middle school) a huge time gap between the AD&D Player's Handbook being released (April 1978) and when the DMG finally shipped (August 1979).
Dragon Magazine #22 (February 1979) eventually came out with a sneak peek at some of the tables needed to resolve combat.
Otherwise, yes, during that gap time there was a lot of homebrew solutions. Cobbling together elements from OD&D, Basic Edition (July 1977), 3rd party supplements (Arduin Grimoire, Jan 1977), etc. You did what you could with content gaps and often-conflicting sources.
