According to my sister who is an active, litvish, shadchan in Lakewood, this was how it was 15-20 years ago (i.e., going without shadchan after 4-5 dates), but now the frum litvish use a shadchan all the way and engagement is discussed through the shadchan as well.
I am referring to below:
“I was wondering the same thing….you can keep the shadchan as a back up support for real issues that do come up…but normally you drop the shadchan and he makes the dates after the 4th (around)
unless you do the 5 dates and engaged…don’t see him during engagement and a year later you get married thing..you never know..I guess to each his own..”