We go every weekend or two, so we don't drain until it's time to winterize.
"Rotten egg" smell is typically related to sulfur...unusual, but not unheard of in well water. Did the home where you got the water have a softener or filter? If so, it's unlikely that water directed to the garden hose faucet would have been softened or filtered. Typically, the "garden hose circuit" in a home with a softener/filter would be split off PRIOR to the water treatment. If you ever fill up there again, ask if you can hook up to the washing machine cold-water connection. It's likely that the washer uses softened/filtered water for the sake of the clothes.
There's no harm in dumping the water in the water heater, and the only risk is cross threading the plug/anode when you button up. An advantage to frequent dumping is that the plug/anode fitting won't seize with rust.
One other suggestion to maintain your water heater would be to get a
hose-end wand that can reach into the heater and flush out calcium and other scale that might build up. Dumping takes care of most of it, but if you have "hard water," and especially if you use the electric heating element (if you have one), the scale can get pretty deep in the bottom of the tank. Chlorine sanitizing doesn't really deal with this issue, but a good flush does. I suspect that when you sanitized then flushed the system to get the chlorine out, you also had a complete exchange of water that removed all the sulfur water.
As with any fresh-water supply hose or fitting, keep this wand clean, or it could introduce bacteria into your water supply. Anytime I handle my fresh-water system, I use a product called Clorox Cleanup to spray hose ends, fittings, adapters, etc. to sanitize them prior to connection. Spray and let it sit for 10 to 15 minutes, then rinse thoroughly prior to introducing the supply into your system. This is an especially valuable technique on hose bibs at RV parks, gas stations, and so on. You never know when a friendly black lab has lifted his leg on your hose spigot!