Before and during the Crisis on Infinite Earths in the mid- to late 80s, Superman and Superman in Action Comics were solo Superman titles and DC Comics Presents was a regular Superman team-up title whereas, after the Crisis, Superman (first series), now called Adventures Of Superman, and Superman (second series), simply called Superman, were solo Superman titles whereas Superman in Action Comics had become the regular team-up title and, a few years later, became a thick weekly anthology for nearly a year.
For a while, when Action was monthly and neither a team-up book nor an anthology, a fourth monthly title and a quarterly were added to transform four monthlies and one quarterly into one weekly with continuous narrative although by different creative teams and the quality went into the Phantom Zone. Things have changed and changed again and I have no idea what is happening now. Alienate old readers as long as you can attract new younger readers if you can.