They spent that summer...

[99bottles]

They (I'm referring to more than two people) spent that summer hanging out all together/with one another.

 

[Tarheel]

Why not "with each other"?

 

[Tdol]

They're fine, though I'd just use together rather than all together unless you are referring to a lot of people.

 

[emsr2d2]

The surrounding context might well mean that you can say just "They spent that summer hanging out".

 

[99bottles]

Why not "with each other"?

I thought it was each other when talking about two people and one another when talking about more than two people. Am I wrong?

 

[99bottles]

They're fine, though I'd just use together rather than all together unless you are referring to a lot of people.

It's four people. Should I use together or all together?

 

[emsr2d2]

They're fine, though I'd just use together rather than all together unless you are referring to a lot of people.

It's four people. Should I use together or all together?

The answer to your question is clearly answered in Tdol's post, which you even quoted!

 

[5jj]

I thought it was each other when talking about two people and one another when talking about more than two people. Am I wrong?

Yes.

A lot of people believe this, but it's not a 'rule'..

[FONT=arial,sans-serif]Usage Note: [/FONT]According to a traditional rule, each other denotes a reciprocal relation between two entities, and one another refers to more than two. This rule requires Dick and Maggie gave each other a knowing look and The members of the graduating class applauded one another. Most of the Usage Panel favors the rule. In our 2005 survey, 86 percent (up from 64 percent in 1987) reported limiting the reference of each other to two things in their own writing. In 2009, 84 percent accepted one another in the graduating class example above, but only 56 percent accepted each other. Still, the rule is often ignored without causing confusion and should be regarded more as a stylistic preference than a norm of Standard English. Many people maintain a further stylistic distinction between the two expressions by using one another when an ordered series of events or stages is involved, as in The waiters followed one another into the room. ·

https://www.ahdictionary.com/word/search.html?q=each other

 

[5jj]

Perhaps you'd like to rewrite post 9 so that it has a less abrasive tone, 99 bottles.

(later) I see you have not changed anything, so I have deleted your post. Please try to be a little less sharp. in your comments.

 

[Tdol]

A lot of people believe this, but it's not a 'rule'.

Most native speakers are blissfully unaware of the distinction.

 

[Tdol]

No, it's not. Define 'a lot of'.

I would not say that four was a lot of people. It's hard to define something that is inexact.

 

[5jj]

I would not say that four was a lot of people.

Quite. It's a lot of people to be riding on one cycle (as I saw more than once in China), but, except when context makes it clear, we would not normally think of four people as a lot of people.

 

[99bottles]

I would not say that four was a lot of people. It's hard to define something that is inexact.

So, do I put a fullstop after hanging out?

 

[Tarheel]

They (I'm referring to more than two people) spent that summer hanging out all together/with one another.

Two things. One, somehow I missed the part in parentheses the first time. Two, I would say they spent the summer hanging out together.

 

[Tarheel]

So, do I put a fullstop after hanging out?

You could.