So, "in 5 minutes" means either "during 5 minutes" or "after 5 minutes" right?

Question

Cambridge Grammar said:

We use in to say how long it takes someone to do something:

He was such a clever musician. He could learn a song in about five minutes.

We use an apostrophe -s construction (in a year’s time, in two months’ time) to say when something will happen. We don’t use it to say how long someone takes to do something:

I won’t say goodbye because we’ll be seeing each other again in three days’ time. We can also say in three days, without time, in this example.

He ran the marathon in six hours and 20 minutes.

Not: He ran the marathon in six hours and 20 minutes’ time.

In oxford dictionary,

in:- during a period of time

in 2009

in the 18th century

in spring/summer/autumn/winter

in the fall

in March

in the morning/afternoon/evening

I'm getting forgetful in my old age.

in:- after a particular length of time

to return in a few minutes/hours/days/months.

It will be ready in a week's time (= one week from now).

She learnt to drive in three weeks (= after three weeks she could drive).

so, Does Cambridge Grammar mean?

He could learn a song in about five minutes.=He could learn a song during about five minutes.?

&

we’ll be seeing each other again in three days’ time= we’ll be seeing each other again after three days?

So, "in 5 minutes" means either "during 5 minutes" or "after 5 minutes" right?

Answer 1

In Oxford's definition, "after a particular length of time" can be thought of as "after a particular length of time has elapsed."

So:

He will return in a few days time.

basically means:

He will return after a few days have gone by.

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As for:

He could learn a song in about five minutes.

a good substitution preposition for this would be within:

He could learn a song within five minutes.

Another way we could convey this is:

It took him no longer than five minutes to learn a song.

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As for during, think of that as "at some point in time during a specified interval".

Therefore:

My daughter was born in January.

means:

My daughter was born on some day in January.

And:

Hurricane Katrina happened in 2005.

means:

Hurricane Katrina happened on some day during 2005.

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Bottom Line: in cases where in means during, that doesn't mean within some interval of time (such as in five minutes, or in two days), but rather for a more specific range of time (such as in the first week of the month, in December, or in the 18th century, or even in the early hours of the morning).

Answer 2

Basically, the preposition in when used with dates and time has three general meanings:

1. During (during part or all of a period of time)
2. No more than (needing or using no more time than a particular amount of time)
3. Before the end (before or at the end of a particular period)

Oxford's definition "after a particular length of time" is probably unfinished because "in" in most cases means "within the limits of a time period". After/afterwards means "following".

• to return in a few minutes/hours/days/months. - to return in a no longer time than a few minutes/hours/days/months.
• It will be ready in a week's time - it will be ready before or at the end of one week.
• She learnt to drive in three weeks - it took her no more than three weeks to learn to drive.

Examples with your phrase "in 5 minutes":

• I'll be back in five minutes. = It won't take me more than five minutes to return. or I'll be back before five minutes pass.
• I can smoke two cigarettes in five minutes. = A period of time (five minutes) is enough for me to smoke two cigarettes.
• I can finish this in one day. = I need no more than a day to finish this.
• The cake will ready in 15 minutes. = The cake will be ready before 15 minutes elapse.