Well according to the GCD, the last Hayfoot Henry strip ran in Action #123, a 4 page story, which was August of '48. In that issue Supes had the 12 page lead, plus a 6 page Congo Bill story, 7 page Zatara story, a Jerry Jitterbug 1 page gag strip by Boltinoff, a 2 page text story called Liquid Metal, and an 8 page Vigilante story. The next issue has mostly the same features but instead of Hayfoot 4 pager, it had a bunch of 1 page gag strips instead by Boltinoff and others, and that looked to be the same formula for a while afterwards. Skipping ahead to look at Action #150 in Nov 1950, the features have changed up, but it is still the Superman 12 page lead, a number of shorter hero strip and 1 page gag strips and text story to fill things out. Skipping to #200 in Jan 1955, it's a smaller book, Supes down to a 10 page lead, only 2 hero back ups, but still a few pages of humor gag fill ins by Boltinoff. #225 in '57 the same thing...so depending what you mean by Superman focused, you are looking at getting near or into the 60s before the humor/gag strips finally petered out in Action...

-M