Even if you have the proper charging system the battery life is dependant on the number of times it is cycled. AGM batteries can be cycled far more times than flooded cells.
Regardless of brand amp hour or reserve capacity dictate how long your trolling motor batteries will last per charge. The entire FLW tour uses the walmart batteries and ill bet they use their trolling motors pretty hard and they manage...hard to beat the price.
I run my batteries all the way down every time i leave the dock and have to charge them twice a day regularly and ive seen drop off in every flooded cell ive tried in a little over a season.