I have done the same for years but I don’t think I actually had much benefit in the end. I don’t ever remember getting spam sent to dodgy-company@mydomain and then needing to block it, in all the 20 ish years I’ve done this.
the reason gmail gets so much spam relative to our individual domains is apparent if the mailer the spammer uses forgets to BCC everyone and you get a list of usernames in the CC: field.
They just iterate over every dictionary word and bolt on numbers and extra letters, or you'll see stuff like genewitci@gmail.com henewitch@gmail.com, etc. I haven't paid attention to gmail in a couple of years since i now use my own domain and fastmail (for $5 a year, even), so i have no idea if the mailing lists are more refined now or not.
Nearly everyone on earth knows about the dot separators and the +whatever that gmail allows, and will just trim that before they sell your email address, nullifying the usefulness. having someuniqueID@example.com is much nicer. you cut down on spam a lot, however it does open you up to a lot of spam to admin@ and webmaster@.