I have never used a tender and even after 6 months expect the car to start, my only charging is the generator while driving, my latest battery is 14 years old, (Optima), the previous battery was used-off the junk pile(5years), before that 7 years from a Delco, and 9 years from a Motorcraft.
The only deviations from a stock electrical system on my car ---diode cutout, and Quartz Halogen headlight bulbs.
Many times the battery maintainer is used as a crutch to cover for other problems such as a draw, poor connections, improperly adjusted charging system ---and using a 1 wire alternator.
A good fully charged battery should not have problems sitting in cold storage for a few months.
I once asked a battery company representative how long I should expect to have a battery last if I used a maintainer --he said 5-7 years ---I asked --5-7 years more??I already get 7-9 years--he said no, the battery should last 5-7 years from new ---he didn't have an answer as to why mine lasted more without using the maintainer ---
A car with a LOT OF ELECTRONICS will need a maintainer to sit for more than a few weeks if the electronics don't sleep soundly(modern network cars)--some of these cars a 35-50 ma draw is normal.