If you look at cam timing diagrams, here's one Google Image Result for http://3.7mustang.com/vb/attachments/f5/81752d1132326110-cam-timing-diagram-800-615-valvetimingillustration-002.gif the point of maximum lift on the inlet happens at something like 106-110 degrees ATDC (After Top Dead Centre) if you look at what's going on with the exhaust on cam timing diagrams, the point of maximum lift is almost always exactly the same number of degrees BTDC (before Top Dead Centre) If you've heard engine tech heads say their cam is "timed down the middle" that's what they mean -the ATDC (inlet full lift)and BTDC (exhaust full lift) figures are the same. Sometimes, usually on high performance cams, the points of maximum inlet and exhaust lift don't exactly match which is when the cam is said to be "advanced" or "retarded" but the advance or retard will only result in a ATDC/BTDC figure differing by a couple of degrees at the most; if you're running problems are due to cam timing your cam is probably out by 5 degrees or more.
IMO it's always worth the time to dial a cam in, Gears aren't always correctly marked by the manufacturer; a motor I re-timed recently after A N Other's rebuild had markings that were way out -the timing gears were probably two odd gears rather than a pair. By dialling in the cam, you either find the markings are spot on and so have the confidence that it's dead right, or you get to fix a problem which is going to cost you BHP, fuel consumption and general aggro later on.
I have dialled in "unknown" cams (usually in Vintage or Veteran cars where there's no data available) with the cam timing set "down the middle" as I described and they've always worked so far.
Having said all that, I would make sure I checked every other possibility before stripping a motor to check the cam timing.