Turning on and off any electronic device is not a good idea. The inrush of current that charges capacitors and energizes inductors does shorten the life of components. This is a fact, not a hypothesis. I always put my MP to sleep after 10 min of inactivity using energy saver. Yes, the hard drives spinning up after sleep do get the same inrush of current. Their MTBF (mean time between failure) is so high, at least 50 000 hours, that they should last at least 5 years. I'd rather sacrifice hard drives than the motherboard of my MP. The only time I shut off my MP, monitor, or printer is during the threat of an electrical storm. Lightning strikes that can and do get into the house electrical distribution system are MUCH nastier than any on-off surges. The POCO's (power company) inability to regulate lightning and transformer overload surges almost guarantees electronics damage in the event of a close power line lightning strike. The main disconnect in your electrical panel can never react fast enough to limit the effect of an overcurrent surge. Whole house surge protectors sound nice, but also are not very effective. The safest thing you can do during an electrical storm is to unplug any electronic device that is of high value. You generally don't have to worry about non-electronic devices like motors (fridge, dryer, A/C, freezer) or heaters. If they have mechanical switches and timers rather than electronic they can take surges that would destroy electronics. BTW, I am a high school electronics instructor and electrician with lots of training and experience.