"one by one" vs "one at a time"

[snade17]

Hi, dear experts. Could you explain the difference in meaning in the phrases "one by one" and "one at a time" ?

[Anglika]

None basically. "One by one" has a rhythm to it.

The animals went in one at a time.
The animals went in one by one.

[RedMtl]

None basically. "One by one" has a rhythm to it.

The animals went in one at a time.
The animals went in one by one.

Agreed provided the number remains one.

However, two by two, or three by three, is not the same as two at a time or three at a time. The "by" implies that the animals, or people, are beside each other, not just trailing in higgly-piggly.

Think of a line of pupils at a school. They line up two by two (or, in two columns, side by side), and proceed forward. If they are sitting down, and two names are called, resulting in two pupils going to the door at the same time from different seats, that is "two at a time."

I agree that for the use of "one" the difference is as good as none. I would be more cautious with larger numbers.

[snade17]

Agreed provided the number remains one.

However, two by two, or three by three, is not the same as two at a time or three at a time. The "by" implies that the animals, or people, are beside each other, not just trailing in higgly-piggly.

Think of a line of pupils at a school. They line up two by two (or, in two columns, side by side), and proceed forward. If they are sitting down, and two names are called, resulting in two pupils going to the door at the same time from different seats, that is "two at a time."

I agree that for the use of "one" the difference is as good as none. I would be more cautious with larger numbers.

Could you, please, say in other words "trailing in higgly-piggly".

[Anglika]

Could you, please, say in other words "trailing in higgly-piggly".

"higgledy-piggledy" = without any particular order, all over the place.