The chairs took a little over an hour to print, but didn’t need supervision. The sleepers took a bit longer but much of that was faff. If I had the right sleeper material and had “dialled it in” I expect it would be an easy hour to cut ~ 170 sleepers but I’m not keen on leaving the laser unsupervised.
The assembly was fiddly, but I’d not done it before and, as I said, you’d probably have the Templot plan stuck down and then glue the sleepers to it, I reckon it would not be slower than ready to plonk track.
edit:
what I failed to mention here is the tedium of pushing chairs onto rail. Same as C&L (and Slaters, I imagine), painful on the fingertips and not quick. I will loosen the fit, which will help, but this does need to be considered. I had some good music on and got better at it, but it’s still a faff.