Yes, an HVAC Smart Chip is very effective in both modes. The primary purpose of the Smart Chip is to diminish cooled or heated air that may be wasted once the fan is turned off. It captures this latent energy so it can be fully utilized. In heating mode, the Smart Chip helps vary the speed of the fan so it can work at its most efficient level and reduce its overall running time. The Smart Chip retains information pertaining to how long your system has been running and runs the fan accordingly, retaining more overall heat from the furnace. This can greatly reduce your heating costs.
In cooling mode, the Smart Chip continues operating to capture cold air that is still being sent through the ducts even after your compressor is turned off. This allows the compressor to cycle on fewer times, increasing HVAC efficiency.