What has been described is all good information, but here is the yeah but:

At design:
Voltage coefficient is the largest concern and for this reason, each cap should be overtightened and then loosened.  General Rule I follow in RC circuits is to try to keep the capacitance as low as possible to counteract the effects of aging.

In production testing: 
So long as the specifications are known, I use a variant of the old Mil-R-39008 (Carbon Comp Resistors) which is group average of 2X tolerance and for individuals, 3X tolerance.  This has been effective in limiting both bad product and test failures.  I also target testing at 60Hz for capacitors to limit capacitance depression from higher frequency and/or source impedance.
These attributes will limit false rejections at Incoming Inspection and ICT.

As for 'refreshing' capacitors:
Baking above the Curie point is not always possible or for that matter even desirable, so I only ever did this on a limited basis.