I see you can buy a conduit bending spring. Does this work with plastic and metal conduit? What a shame the conduit is 20 or 25mm and not 22mm otherwise one spring could be used for plumbing and conduit. I dare say there are proper conduit benders but for one-off use, a spring is probably the only sensible way forward. Do you use them as you would with copper pipe: insert spring, bend over knee, and then bend back slightly to release the spring?
I would have thought that big angles, say 90 degrees, were asking for trouble: presumably you make the bends as gentle as possible to aid cable threading?
Is it a good idea to bend conduit or it it better to buy the joins? The corner pieces usually have a lid that unscrews, which enables you to help push cables round the corner when installing/removing them.
What if the conduit was buried inside a wall. Wouldn't I need something behind a blank plate, not only so that I could access the bend but also to show that the cable changes direction? I thought there had to be an "accessory" wherever the cable changed direction?