I built up my ability to run slowly, and occasionally ran without the orthotics. Or rather, tried to run. My legs were still really quite weak when it came to running. They would tire very easily - the calves would effectively seize and stop working, and I found it impossible to manage more than 2km unless I resorted to running in a style more similar to race-walking (something I had done quite a bit when younger, thanks to Little Aths). I gave up on not using the orthotics and decided to just work on being able to run, or at least have the aerobic capacity to run.
When the time came to pick up another pair of shoes (this was after a second pair of Wave Riders), I went back to the treadmill at the Running Company and the result was the same as the last time I was there - it still didn't look like I needed the orthotics. With a bit more confidence, I picked a pair of shoes that felt fine as they were and without orthotics - the Saucony Triumph. I remember my first run in them, a short run taking the long way to uni. It would only have been about 3km, and I don't recall feeling bad during the run but my calves hated me the next day. The next time I tried the Triumphs (alternating with the second pair of Wave Riders) was with the orthotics, and I didn't have any problems on the run or the day after.
My orthotics were set up for me because of imbalances in my legs when running (and walking), and the physio always thought that I could get by without them at some point if my legs were strong enough. So ditching the orthotics wasn't an aim of convenience (as it is annoying having to move them about from shoe to shoe), but an aim that would indicate progress in leg strength and in running ability. As long as I kept going to the gym to work on the right leg strength exercises, I would be able to ditch the orthotics.
But lab experiments took up time and eventually ruined my hands, so I found I didn't really have the time (or ability) to go to the gym, and my legs felt weaker and weaker. I stuck to the Wave Riders and the orthotics, occasionally using the less supportive Triumphs on shorter runs but never being truly comfortable in them.
It wasn't until after I'd moved back to Melbourne, got back on the bike regularly and ended up ditching the orthotics on the bike that I started to feel like perhaps I could get back onto the "no orthotics" horse. I suppose the bike had been strengthening my legs for running more than I realised, as I found I could use the Triumphs without the orthotics for runs up to 5km or so without any problems whatsoever. I didn't even need to build up to the distance!
I wasn't sure if I could manage the Puffing Billy run's 13.5km in the Triumphs, so I stuck with the Wave Riders for my long runs, and thus also for the Puffing Billy. The more I ran in the Triumphs, the more I realised I really didn't like the Wave Riders anymore.
It's now been six weeks since the Puffing Billy run, and thus six weeks of only using the Triumphs and not using orthotics. I've done a few 10km runs in them (although most have been two 5km runs with a short break between the two chatting to parkrun folk or driving to another park) and everything feels fine. No calf soreness, and my arches don't feel like they miss the support from the orthotics!