Is it just a matter of keeping the summaries short?
Well, in a manner of speaking, yes, I think that is a part of it.
If nothing plot-worthy happened in seven weeks, you might begin after a text break by saying, "Seven weeks had passed since..."
That's a pretty short summary, but it feeds the reader info that, oh, okay, obviously it was a pretty normal seven weeks. And if not, you give attention to what happened in that time span with an amount of words equal to how important it is to your story (IMO).
"Seven weeks had passed since Morton's death, and Elizabeth had only cried once, on a Thursday afternoon when the sun caught his glasses on the windowsill a certain way."
or
"Seven weeks had passed since Morton's death. It had been only a week, though, since something seemed to have broken in Elizabeth's brain for good. For instance, on the second day of that week, she dug up Morton's grave at damn near 3 a.m. and danced to a battery-powered radio with his corpse. He in cardigan and slacks, she in a lacy evening gown number. Nick LaRocca played. On the third day..."
Just depends on what you want to show, I think.
EDIT: sorry, it appears a few folks gave similar advice already. But. I like my examples so I'm leaving my post for historical reference
