I advocate recapping every 10 to 15 years because the manufacturers of electrolytic capacitors have always stated "five year shelf, 10 year operating life" for all but high spec long life elevated temperature caps. For example, caps rated at 4000 hours @105 degrees C. It's a prudent policy aimed at keeping your amp healthy rather than risk expensive damage if you should end up with caps that fail in service.
Sure, they'll usually have a usable service life longer than that. But two things: A lot of guitar amplifier owners don't have a clue as to why maintenance is needed so they don't do it, and as a result, I've seen lots of 30 year old amps with their original filter caps. There's zero chance that this amp sounds right even if it's working without apparent problems. And I've seen more than enough amps where the filter caps had completely failed and burst or spewed corrosive electrolyte everywhere, that WEREN"T yet 20 years old. So I recommend service more often than Mesa does simply because the evidence in front of me indicates that this is a prudent choice.
If I'm more conservative and pessimistic than Mesa's service department, I call that a good thing. Mesa does a number of things that I find to be highly questionable if not outright BAD ideas in some of their products. Bad sounding tantalum capacitors in an audio pathway? Seriously? Amps that lack adequate cooling (studio 22) and slowly cook themselves to such an extent that they desolder themselves? High voltage lines running absurdly close to each other? (Rocket 44 yellow and white wires running from preamp board to output tube board. Spacing is absurdly small for the voltages carried.)
Mesa remains my brand of choice but speaking as an electronics tech of broad experience spanning more than 30 years and counting, I don't think for a moment that Mesa's designs or execution are necessarily perfect. It's generally pretty good but there are things in some Mesas that just make me think "What on earth are you guys smoking? :shock: ".
If I had a Mark IIC+ land in my lap I'd send it off and have Mike give it the full red carpet treatment. But it's a legendary amp, and well worth it. For more ordinary amps, routine service, caps, glass, check bias, clean pots and jacks, done by a local GOOD tech, should be sufficient. However in any event I still advocate getting the caps from Mesa. There's no reason not to. The price is right and the quality is best in class.