if anyone can do it in 30mins, and do a proper job then i will give u half a slab.. has to be properly timed.
It usually takes me a bit over an hour... thats getting the tools out, undoing everything, removing plugs.. having a look at the old ones and numbering and dating them, then gap the new ones and put them. Do everything up... and presto...
Add another 5 or 10 mins if i put my tools away, but im too lazy after that to bother and normally do that a few days later