I've never warrantied a screwdriver. If they get dull, I renew the tip on a grinder. I've broken a few tips, but not driving screws, so I figure I abused it, so it's outside of warranty. Besides, I have so many screwdrivers, if I break one, I have another to back it up.
Most of the time, for phillips screws, I use a cordless drill with a phillips bit. I buy those by the replacement pack (25-30) so when one breaks or rounds off it just gets pitched.
Dale