I think that sometimes the pronoun "one" is not ok for some reason, but...

Don't take the blue book, take the red one.<-- Ok. This is a normal sentence.
There is no reason why you should consider British English better than (the) American one.<-- Suspicious for several reasons, especially if you leave out "the". I would just repeat "English".

I was just trying to figure out when "one" does not sound good. Could it be that it's not used when it refers to an uncountable noun without an article of any kind?

It's better to have a general knowledge of this subject than a specific one. <-- This seems ok, but I am getting paranoid so I am not even sure anymore.
It's better to have good knowledge about few things than bad one about everything. <--- This is suspicious.

Can anyone come up with some advice? Can you think of any examples where "one" would sound odd as a pronoun? Thanks. Emotion: smile
You are on the right track!
One is a pronoun and has to reference a noun. Because 'one' means a single item (or ones, more than one), it does not work to reference a word that would be a non-count noun (English is dicey, but knowledge is surely non-count).
I like green cheese, not the blue one. --> This is not correct, since "cheese" is non-count.
Correct: I like green cheese, not blue.

I like the green cheese better than the blue one. --> It only makes sense if I mean a "round of cheese", which is countable.
There are green, red, and blue lights. I like the blue ones better.--> One has to be plural to match its antecedent.

This is OK too - where "one" is singular, but refers to the plural "subjects"

It's better to have a general knowledge about many subjects rather than detailed knowledge about one.
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Recall that * means ungrammatical.

one is always countable.

*coarse sand and fine one; *white sugar and brown one; *fresh milk and spoiled one; *British English and American one; *good knowledge and bad one

But (countable):

a happy child and a sad one; happy children and sad ones; the happy child and the sad one; the happy children and the sad ones

a big shoe and a small one; big shoes and small ones; the big shoe and the small one; the big shoes and the small ones


The indefinite determiner a, a possessive construction, or an adjective of quantity cannot be followed directly by one; however, an adjective may intervene.

this old one, this one, that new one, that one, the fast one, the warm one, the one, a gold one, *a one, my old one, *my one, Tom's old one, *Tom's one, many new ones, *many ones, several good ones, *several ones, three short ones, *three ones

(these ones, those ones in some varieties of English; *these ones, *those ones in others.)


With an adjective modifier:

the tall statue and the short one

Father's big shoes and Mother's small ones

the English teacher and the French one

-- The teacher from England and the one from France

With an adjunct:

a book with red trim and (*a) one with blue trim

the chair in the living room and the one in the kitchen

the coat that Lucy bought and the one that she stole

With a noun modifier:

*the clothing store and the hardware one

*a science book and a Latin one

*Father's work shoes and Mother's dress ones

*the chemistry teacher and the physics one

*an elm tree and a maple one

*Kluckin'-Fresh eggs and Lay-Rite ones

*the English teacher and the French one.

-- *the teacher of English and the one of French.

With a complement:

*a way of speaking and one of singing

*the Indian form of English and the Latin American one of Spanish

*a good knowledge of linguistics and a passing one of philosophy
I have used "and" to connect noun phrases above only for purposes of illustration. The grammaticality of these expressions remains the same even within other structures within sentences, for example,
The tall statue was more beautiful than the short one.
*We planted an elm tree, but not a maple one.
*They shopped at the clothing store in the morning and at the hardware one that afternoon.
Wow, those were all things I felt unsure about! Now I understand, but let's hope I'll remember what I just learned, LOL. Thanks.