I was going to go with what Sac said, but do you have any particular specific things you'd call a "proficiency flight"?
I don't practice engine-outs necessarily every flight, for example, but I do at least one or two a year besides any CFIs beating on me. Pull the throttle and pick a spot out on the plains...
Same thing with steep turns, stalls, and other required items in the PTS. Not every flight, but certainly more often than the guys and gals who only bother with them during a BFR.
Any flight can have a challenge added. Leave the iPad on the floor and grab a chart and don't set the DG, for example. Or just keep a PTS book around and randomly stick a finger on a page and do that stuff that flight.
Or go see how soft or short you can make your landings today... Or find a dirt strip and play on the dirt...
"Anyone can make any flight into a refresher flight" -- is probably a slightly better way to think of it than Sac's statement, I guess. But he's also right.
I tend not to subject passengers who are non-pilots to maneuvers, unless they've specifically requested them, and their sick-sack is available.
I attempt to give them a good experience instead. But solo, I'll throw a steep turn or two in during cruise (after slowing up a bit perhaps, over something I want to look at) or pretend the Nav has failed just to see where dead reckoning takes me.
Or not. Sometimes I just want to enjoy the view.