Some folks like to cycle their servos prior to insallation. This 'burn-in' can detect a failed servo. Most electronics, if they are bad, fail early on.
I like to use a ToolKitRC ST8 servo tester. It can cycle up 8 servos simultaneoulsy, but only do up to four at a time.
This servo tester displays the servo current and speed (depending on the mode).
I was testing four servos (no load) and noticed one was a bit warmer than the rest. I looked and indeed it was drawimg about 25% more current than the others. It also buzzed when at idle.
The manufacturer told me its within normal parameters, but I do not trust it. I think the gear train is slightly binding and this casues it to work harder. I opened it up and it was well lubricated and all looks well - but the slightest error can cause issues.
The servo current peaks when. the servo changes direction - I'm seeing 500-700mA as normal, and 800+ as an issue. I'll have to look and see what the cycle speed is for my testing, it is aproximatley 1.5 seconds per 60 degrees. The faster the servo is moved, the higher the amps.