I have used Battery Tenders for about 15 yrs. Before that, I used one of those switches on the similar to this:
https://lmr.com/item/BDS-14301/79-04-Mustang-Top-Post-Battery-Disconnect-Switch

My experience with these switches is only good for the season you are using the car. I used these switches but in the end, my batteries were lasting 2-3 yrs. I'm guessing its because the batt is switched off during a long Fall/Winter period. That gets expensive buying batts that often.
That is when I went to a Battery Tender. On my Turbostart agm red cap battery, it is working great since 2010. I never had a battery last this long. Now I leave the Batt Tender on the battery all Fall/Winter storage and when Im not driving the car in my garage and it keeps my clock ticking. I have gone thru 1 batt tender that lasted about 8 yrs. All that happened was the Grn and Red LED stayed on ALL the time. Never turned Green only. Stuck a new one on, my batt is still going strong.
I would not use the Batt tender that is 1.25amp on a small motorcycle type battery. I used this Batt tender on my Honda Generator with the small m/c battery. It did dry it out. Get a Batt tender that is .75 amp for m/c batteries. For me, love them.