I would take the back cushion off the seat on longer flights in the freighter Lears so I could stretch out my legs. The passenger 35s I flew had the Ipeco seats that were bigger and more comfortable but since they were bigger they made the cockpit more cramped than what we had at Airnet. And you couldn’t take the cushions off of them either.
A few years ago I did upset recovery training at Calspan in their Lear 25 after not being in one for years. At the end of the ground school we went to the hangar for a briefing on the jet, how to work the door, emergency equipment, etc. I got in the cockpit with the instructor last and the first thing he asked after I sat down was how much time I had in Learjets, since only people that had been flying them for a while get in them like that.