[magduf]

Um, I'm not so sure about that. Sure, there's a lot more strings on a piano, but they're all separate from each other, and once one is tuned, it's tuned and you can move on to the next one.

Try tuning a guitar that has a Floyd Rose locking tremelo system. The bridge is floating on a pivot with springs, so the tension of the strings is collectively working against the 2 or 3 large springs on the bridge. So every time you tighten or loosen one string, you're changing the tuning on the other 5! And adjusting intonation is a pain too, because if you finally get the strings all in tune, then when you adjust one string's intonation, it throws off everything again. (And worse, to adjust the intonation on a Floyd Rose, you have to completely loosen the string so you can get to the tiny little hex screw to unlock the intonation adjustment, and the way it's designed you don't really have an easy way of fine-tuning it.)

[elektronaut]

Pianos are like that too. There is a LOT of string tension, and the soundboard warps. Raising the pitch requires carefully balancing by tiny adjustments in several passes.