Thanks Haggis, that was it. It seems so obvious now--reflexive pronoun WOULD be reflexive only if the subject was SHE. lol... Time to go to bed.
Wait a minute. In your sentence the verb "extricate" has no subject. "It" is the subject of the verb "took", and it's therefore wrong to say:
It took herself five minutes...
But who would ever say that (unless it's a slip)?
"to extricte herself" is perfectly okay in your sentence. Take the minimally modified version:
It took her five minutes to...
If you add "her", there's no confusion whatsoever. So the question is whether you need the "her", and if you don't whether you have a better sentence when leaving it in or taking it out.
When you make general statements, it's quite common to leave out the direct object of "take":
It takes at least five minutes to extricate oneself/yourself...
Notice that the pronouns ("oneself", "yourself") are indefinite pronouns, here. ("You" is technically a personal pronoun, but it's used with a general meaning as an indefinite one, much like "singular they").
If you describe the
agent of the verb "extricate" in more detail, you'll have to add the direct object of "take":
It takes a woman at least five minutes to extricate herself...
Now you can't use "one" or "you" anymore, because you've made the agent more specific and women require "her". (Note that you can't leave out "a woman" and still use "herself")
But what you're doing is different. You have a specific situation.
A: Hey, yesterday, I managed to free myself from Joe without waking him.
B: Cool!
A: Yeah, it took at least five minutes, though.
Do you really need "me" in the last sentence? ("Yeah, it took
me at least...")
I think that the direct object in the "It took [one] [time] to [verb]" construction is optional, if we can work out in context whom it took that time. In short, I don't see any grammatical problem with your sentence.
Actually, the verb that relates to the reflexive pronoun could be part the subject:
Extricating herself from his arms without waking him up took five minutes.