Give songs a length, and the builder totals your sets.
Give a song a length in the song editor, as minutes and seconds ("4:30") or plain minutes ("4.5"). Add Multiple has a Length column too, so a spreadsheet paste can carry durations along. Attaching audio to a song fills the length in for you; see Audio and transition previews.
Each set header shows a running length, and the setlist header totals the whole show, updating as you drag songs in and out. Timed notes count too, so two minutes of band intros do not vanish from the math.
A song without a length counts as 5:00, and any total leaning on that default is labeled (estimated). Hover the label to see which songs still need a length. Fill them in and the total turns exact.
The builder's library filters include a length slider. Drag it down to hide everything longer than the gap you are trying to fill, or leave it at the right end, "Any", to see the whole library. Songs without a length wear a "~5:00" tag, which doubles as a list of the songs still waiting for one.
Setcraft is a Mac app for working musicians: build setlists, print them big enough to read from the kit, and keep every song your band plays in one place. Download it free for 30 days.