solid state gear- leave on?

Well designed electronics are not "stressed" by turnon and turnoff. Fifty years ago my tube power amp had a "soft start" circuit. Actually it was just a wirewound resistor with a bimetalic strip with switch contacts on it. The resistor was in the AC power line, so that initial turnon was at reduced voltages, but when the resistor got hot the contacts on the bimetalic strip closed and shorted out the resistor so that full voltage was applied. Must have cost about 25 cents. Nowadays a "soft start" circuit is probably more sophisticated, but there is no excuse for the designer to completely ignore the turnon requirement.

My digital power amps have a turnon sequence which they execute, and it even includes diagnostic checks in the process.

Sean...Of course "Well designed" applies to the protective circuitry also. Protective circuitry should be designed so that it does not affect performance. If this is a stated requirement it can be done. This rule applies not only to performance, but also reliability. Any protective circuit, if it fails, should not affect operation, thereby degrading reliability...false alarms should be recognized as such and disregarded. (Come back and fix them later).

There are two schools of thought regarding the merits of "Continuous Operation" of missile guidance systems. Some are kept "spun up" and ready to go all the time. Some are kept in a temperature-controlled "dormant" condition, and only spun up within minutes of launch (if I said how many I would have to kill you). Of course there have been intensive studies regarding the effect on accuracy and reliability of the frequent spinups and shutdowns of the dormant systems, and the bottom line is that, if the system is designed to be operated this way it is more reliable than continuous opearation. This is contrary to what people tend to believe from their everyday experience with light bulbs, which always die with a flash on turnon.

You are right that additional circuitry will TEND to degrade reliability, and can affect performance UNLESS the designer addresses these issues.

Artizen65...Slight correction. The money saved by improved reliability through use of dormant mode, rather than continuous operation, is TAXPAYER money, not mine.

Continuous Operation was proposed several times over the years while I was involved, sometimes by the customer. In every case, upon objective study, it was determined that people's "gut feeling" that reliability would be improved was wrong. Of course, it is relevant that the equipment was designed expressly to be operated in this manner. I suggest that all equipment should have at least simple provisions to avoid adverse effects from power application/removal.