The primary problem with balance over time is that it assumes a group will start at first level
Yes, as far as I'm concerned that's a given.
and advance enough levels for it to kick in.
This, I admit, is more of a headache. Most games manage at least 1-10, though, so if things even out over that span you're probably more or less good.
When I played BECMI, AD&D 2e, and 3e, a lot of people started at third level just to have some measure of survivability. Plus, few campaigns ever had characters get very far into the double digits, especially the classes that were designed to shine at later levels and who advanced at slower rates in BECMI & 2e.
I'd never start at anything except 1st (and what is this strange thing you call 'survivability'?)

but when I'm tweaking stuff I try to look at 1-10 or maybe 1-12 instead of 1-15 or 1-20.
If you balance at the character level, then you can start at any level, play to any level, or even never gain any levels at all and be balanced for the whole run.
True, though at cost of denying or closing off some design options.
Ganymede81 said:
But yeah, you are right on one level. If I allow that E Coli contaminated beef is OK, I've opened myself up to a huge amount of new culinary experiences.
You're equating longitudinal balance to poison?
Bang out of line.
TheCosmicKid said:
In a game where a party can spend weeks, months, or the entirety of the campaign at a given level... that's not "micro balance" any more.
I've seen (and run) campaigns that spent weeks and-or months at
each level - in fact, that's what I prefer - but never seen an entire campaign (other than one-offs) stay at one level. Sometimes macro balance does take years to manifest, but then my campaigns tend to be many years long.
Obryn said:
I think Dungeon Crawl Classics, for example, is an outstanding game, and it sticks to unified advancement and gives all the classes cool things to do at each level.
DCC is fine unless you're a wizard, in which case the only question is how long it takes you to turn yourself into a twisted wreck of your former self because of all the side effects of casting. I found the system really appealing (for example I love love love the funnel method of character generation!) until I hit that bit, which turned me off it. I thought about ways to tweak it out but couldn't find anything that worked while keeping the spirit of the system vaguely intact...and so, I didn't change to it.
Lan-"the best use for 'balance' is as an old restricted white Magic card that could save your bacon in an otherwise lost game"-efan