With a half decent program (I use Navbox Pro for UK VFR) you can do the route and get wx and notams in 10 minutes, with everything printed out and ready to go. Anytime in the past 10 years there has been no reason to do things the hard way, with the stupid circular slide rule and all that crap.
True, but as you well know, for a longer flight that takes you out of the local area, there's all sorts of other things to sort out. Proper charts, endless lists of irrelevant notams, checking the status of R/D/P areas, getting PPR, confirming fuel, keeping an eye on the long-term weather, confirming parking space, booking taxis, hotels, sorting out foreign currency, ...
The actual plog calculation is only the culmination of all that effort. Whether you do that via navbox, iPad or something else modern, or via the old-fashioned E6B isn't really relevant, other than the E6B taking a little more time.
A few years ago we had a club flyout to Berlin Tempelhof. Most of us were relatively inexperienced. The first planning meeting was three weeks or so in advance, the second about a week in advance and the final planning meeting was about two hours before we were scheduled to leave.
With experience this gets better of course, but I'm sure that even you can't plan a flight to, say, Croatia within ten minutes from absolutely zero to startup.