As my precious DH is prone to say, "They don't make houses like they used to."
Followed by a heartfelt, "Thank God!"
While we love redoing older houses and have enjoyed the mess our son has in his 1832 Victorian, it is true that nothing is 'standard' anymore, the years have caused settling in unexpected (and expected) places, and you never know quite what you will find once you start a remodeling project.
Lucky for us, DH is a carpenter of the old school and can correct changes, we have the power tools in the workshop to plane rough cut lumber to correct size, and the cutters to match almost all the trim styles.
No, they don't make houses like they used to. I love the look and feel of craftsmanship and love of wood that went into well built houses of old, but many times badly built additions, old wiring, lead plumbing, and inadequate heating in those old houses make them money pits pure and simple. Beautiful, stately, irreplaceable money pits.