Today coaches corner is all about the merits of hills and / or riding the flats. Why and when will aid you towards achieving your goal.
Winter hills: winter is all about building that strong base. Making your legs stronger will aid you come the increase in intensity during the season. Riding hills takes practice, knowing what gear to use, what cadence range, how much power you should be generating. Either way, riding hills will make you stronger. BUT if you only ever do hills, then will lose that cutting edge which riding the faster fasts can do, (see below).