If a battery is completely dead, it's for a reason. Leaving the lights on over a weekend is a reason and draining a battery all the way down will damage it. Any battery that's been drained completely down will likely be damaged and I'd rather not be dependent on one 20 miles from nowhere. Draining a good one once by leaving something on won't hurt it substantially but a number of times doing that will cut the power it can put out.
