In reference to draining the hot water heater when winterizing. YES, you always need to remove the anode when winterizing your trailer. It is the only way to be sure you are draining ALL the water out of the water heater during the winterizing process. Also, when your doing this, open the high pressure valve on the heater and it will drain completely. AFTER, draining the hot water heater, you can open the bi-pass valve to bi-pass the water heater and finish the winterizing process.
It is not necessary to drain the water heater between uses during the summer. I would, however, drain the fresh water tank after each weekend usage.
The every year anode replacement should be a guideline, not a rule. The condition of the anode when you winterize will determine if it needs replacement or not. Use your good judgement on how much of the anode is "eaten away". I guess I'd replace it if its 35-40% gone, otherwise, use it another year.
Days camping (2015)----88 days
Days camping (2016) ---110 days
2016 Wildcat MAXX 28RKX (33' TT), 2007 13' Scamp
2015 Ram Laramie Hemi
30 years RV'ing
12 different RV's