Continuous insulation is the last (and most important) line of defense when it comes to keeping heat inside a structure. Heat is transferred through studs, so if insulation is not installed continuously across the building envelope, a structure is not living up to its potential in terms of thermal performance.
When combatting internal temperature fluctuations, certain factors cannot be controlled, such as our seasonal distance from the sun, or the warm and cold fronts that make up part of the daily forecast.