A bigger capacity battery is only any good if it can be charged fully?
My commute is about 20 miles each way, which takes me approximately 30 minutes + whatever hold ups I encounter, that's more than enough time to recharge the battery on a cold winters morning or evening, even with lights, wipers and heater all on, but if the journey is less than 20minutes you might put you on dodgy ground, and repeatedly doing short journeys could lead to an early end for your battery.
The Jazz rearly sits for more than a few days without being used, this time of year I use my motorcycle for work, but the Jazz when out shopping or with family etc.
However my Land Rover sits for weeks without being started without any issues, but it has a much larger battery as it's a diesel. I have left it for several months on occasions and it can struggle and need a recharge first especially if it's been cold.