How long does each type of action take?

[Yqatuba]

I've never been clear other than with full-round actions. Considering a round is 6 seconds

Full-round: 6 seconds (or maybe slightly less, as you can still do a free/swift/immediate action)
Standard: Maybe 2-3 seconds?
Move- About the same as standard, maybe a little longer?
Free/swift/immediate: unsure, but very short (maybe 1/10 of a second.) particularly for free actions as you can take as many as the DM deems reasonable.

[Kimera757]

I assume a standard action is over 3 seconds, because you can only do one within 6 seconds. A move action has to be more than 2 seconds, because you can only do two of them (and less than 3 seconds, because you can do one and a standard action and still have time for a free action, etc).

So I guess a standard action is 3.5 seconds, a move action is 2.5 seconds, and a swift action is less than a second. I don't think any action not involving magic takes less than a fifth of a second, because of human reaction speed. (Yes, some PCs are not human, but generally human PCs can do the same things non-human PCs can.)

[Chell Raighn]

So as outlined in the rules, a full round is 6 seconds. In that time you get a move and a standard action, each at 3 seconds. Free, immediate, and swift actions are assumed to take place simultaneously with your other actions.

Your move & standard actions can also be assumed to be 2-2.5 seconds leaving an extra 1-2 seconds of time for actions taken out of turn and swift actions that can’t reasonably be taken at the same time as a normal move or standard.

In full the action economy over an entire round of combat with all combatants is a bit wonky given that it all happens in the same 6 second time frame... which always makes it weird that a participant may be unable to act at all in a round if they are incapacitated by someone who went before them but who spent 3 seconds(or more) not attacking them...

[Sandslice]

There's an understanding that unless you're flat footed, you're doing stuff that doesn't pertain directly to mechanics, such as minor feints, positioning, gathering mana to prepare to cast, etc.

This is still as true as when rounds were a minute.

[Meirril]

A round is 6 seconds. Individual components of a round get performed during that 6 seconds but don't have a set duration. Swift, Move, Standard and Free actions probably overlap significantly.

A few examples: Someone that casts spells probably begins to prepare components needed while moving and performing evasive actions which continue as the spells is performed. Even a caster that doesn't technically move is not just single mindedly casting a spell but rather is trying to observe the situation around them while casting and reacting appropriately.

A fighter that takes a full attack and move 5' to position themselves isn't likely to do a flurry of attacks and then suddenly side step. More likely the flurry of attacks were accompanied with several small adjustments to reposition the fighter 5' during the round. And nobody accounts for the time spent defending themselves during the 6 second round.

A bard performing a song while shooting a crossbow doesn't have a noticeable period of time where you think they spent a free action to continue their performance. During the process of reloading, aiming and firing the crossbow they just keep performing as well.

Also keep in mind, the actions of everybody happen during the same 6 seconds. That includes the enemies actions in return.

[Quixote]

Meirril's got it the only way I've ever been able to accept it in terms of how it translates to a real-life situation.
I guess if your campaign setting was an bit arcade scroller or something you could justify a set duration to each action.