Critical Points across the Levels

[MukkTB]

At what levels does gameplay change drastically?

I know an argument E6 claims that it caps off levels while fighters still represent a serious threat to casters.

I've heard both lvl 1 and lvl 20 gameplay being referred to as rocket tag. At low optimization rocket tag seems to end around lvl 3 or so. But at high optimization it seems that all levels have rocket tag characteristics. Ubercharger anyone? What levels are generally not considered to be rocket tag?

To be basically competent with a skill seems to require several levels. The same goes for melee. +1 base attack feels tiny compared to a D20 but a +4 or +6 seems competent. Do people generally agree that lvl 1 represents a slub or an apprentice and you need more than that to be a real artisan or fighter?

'Linear Warriors Quadratic Wizards' implies that wizards become more powerful than fighters at some point after the start. However I've seen (cheesy) optimization that implies that its that way right at lvl 1. Some people say 3 or 5 is when it happens. And then obviously a Druid with a replaceable animal companion is just better than a fighter. Do fighters get a moment in the sun at low level before the casters totally overshadow them? How about other nonmagical characters?

Are there other changes in gameplay that occur at higher levels that I'm not aware of for not playing to those levels?

All of my questions are asked in the spirit of lowish-mid level optimization and I'm looking more for what actually happens in game than theoretical optimization.

[Flickerdart]

You don't need cheese - a 1st level spellcaster casting Sleep or Colour Spray is statistically better than a 1st level Fighter swinging a sword. The only reason Fighters remain competitive here is that spell slots are still a real limit at this point. They stop being so around level 9, when a Wizard can cast one spell every round of every encounter for the day and have some left over at the end. Most of the really powerful spells also come online at the middle levels (7-11).

Melee power also crests around 9th level, when you've picked up all the necessary feats to string together whatever combo you've been going for. At this point, you're probably reliably killing people in one or two hits, and all your resources from now on will be spent simply keeping up.

I suspect that a major contributing factor that E6 stops at 6th is that it's a really nice cap level numerically. Full BAB gets an iterative attack, everyone gets a feat, Sorcerers get their spell level. These things don't align at any other point in the game.

Thus, the game starts changing rapidly at the mid-levels, and the less you're optimizing, the more you'll notice it here, as monsters with SLAs, movement modes and immunities start coming online.