Learn English – “Details on” or “Details about”? Use in technical writing

The problem here is that there is not one true answer. Google will display the various styles used, but there is not one correct one.

To determine the style that you should should use, do the following.

Look up the word in the standard dictionary you are supposed to use. (If there isn't a standard dictionary for your project, choose one). If the word is in the dictionary, use that spelling. If not, look up the hyphenation rules in the style manual you are supposed to use. (If there isn't a standard style manual for your project, choose one). Hyphenate the word according to those rules.

For questions of capitalization, you'll have to refer once again to the style manual. It should contain rules for capitalizing hyphenated words. But be aware, the capitalization rule for a hyphenated word in a title may differ from that at the beginning of a sentence.

Example

Let's use your word, "co scheduling", and the rules from the Penn State Editorial Style Manual.

The manual specifies "Webster’s Collegiate Dictionary, current edition" for spelling and hyphenation. In that dictionary there is no entry for a word co that would properly modify scheduling, which means that "co scheduling" is incorrect. There are also no entries for either co-scheduling or coscheduling, so we can't follow the dictionary's spelling.

There are entries for the prefix co- and the word scheduling. So the word must be formed by merging these two. We need to use the style manual to determine how to do that. The section on hyphens states: "Words formed with the prefix co should be hyphenated." So if you follow Penn State's rules, the word should be co-scheduling.

The Penn State manual is silent on the rules for capitalizing hyphenated words and refers users to the Chicago Manual of Style in that case. That manual states: "Do not capitalize the second element if (a) it is a participle modifying the first element or (b) both elements constitute a single word." Because co- is a prefix, that means co-scheduling is a single word, and therefore the capitalized form is Co-scheduling.

Doubtless some will say NGrams isn't appropriate here, but I think this is interesting...

Obviously many of those instances are "false positives" (particularly, the earlier ones). But the increase in prevalence is quite marked, and glancing through a few pages of the later instances shows that many of them are indeed the construction OP asks about.

Structurally, what seems to be happening is that two separate elements (for example, "the thing is" and "is that") have both become grammaticalised in the mind of the speaker, so they're seen as independent self-contained grammatical items - each containing its own copy of the word "is".

As the chart suggests, it's very much an emerging usage that's gradually extending its scope, so...

"What it is is that blah blah" - seems unremarkable to me.

"The point is is that blah blah" - sounds somewhat "off", but I can live with it.

"The problem with this is is that it sounds weird" - to me, at least, it really does.

Different speakers will draw their own line as to where the construction becomes "unacceptable". Some people may think it makes a difference whether there's a comma between the two instances of "is". But because this is (still?) primarily a spoken usage, and people don't punctuate speech, I think that's largely irrelevant.

Addressing OP's specific question, I'd advise against using the form in "professional" writing for the two reasons mentioned above - it's mainly a spoken rather than written usage, and not everyone will be happy with it in any given context.