The way that Dan Curtis and the DS writers interspersed the time travel periods on the show with the contemporary story lines afforded the actors the opportunity to portray other characters, and remain fresh in their performances. I believe that KLS once said that she particularly enjoyed portraying other characters in the various time periods, and not just having to portray Maggie Evans all of the time. Besides, it would have become extremely tiresome to see one current day catastrophe immediately after the other on the show for nearly four and a half years.
One criticism I've had about the 1897 story line, however, the longest time travel story line on DS, is how DC and the writers ended the story, seemingly, so abruptly. I don't believe we ever got to learn what happened to the irrepressible Magda Racosi or to the stuff-shirted Edward or to the shrewish and miserly Judith Collins-Trask for that matter. After nearly nine months, we never got to see what happened to these remaining 1897 era characters, who were always compelling, charming and, at times, even exasperating.
As to Maggie's future with the Collins family, DS writer Dale Clark, in his series of superb DS novels, suggested that Maggie became Mrs. Stoddard's personal assistant/aide after David obviously became too old to have a governess anymore. (I think that Dale also suggested that the unfailingly jittery Hallie Stokes left during 1970 to attend a high school somewhere out of Maine.)
Alas, we'll never know what
might have happened at current day Collinwood after April of 1971.