The guy at my local bike shop says i don't need to use either the plastic valve covers or the lock nuts on my presta valves. he says the only reason the tubes come with the plastic valve covers is so when they are folded up in your bag, the vavle stem does not damage the tube. He says he does not use the lock nuts because they can stress the tube at the base of the stem, they make a stem that is not lined up correctly with hole in rim look straight and ultimately they don't do anything good except hold the stem out when filling.
What are your thoughts? this isn't a big deal, but it would be nice to not have to screw those nuts on if not necessary (i do have long stems, takes some time) It would also be nice if i didn't have to get down on my hands and knees and look for the stupid plastic valve covers every time i drop one (happens at least 2 times when i change tire... used to hold it with my teeth until one day i couphed and ate one!!)