Seems nobody is pressing foreward as a volunteer answering this question.
I, on the other hand, can only give a very unsatisfactory answer: We have to take it.
Conditional formatting was enhanced some time ago with the release of one of the 3.x versions.
Before that only 3 conditions were supported and there was no 'Manager' but just a simple dialogue. Editing an existing CF required knowig the exact range first (as I remeber - if correct). This may have helped to establish a reasonable restraint on using CF in a too complicated manner. In addition: We couldn't see the mess we possibly had caused. These times are gone. The current implementation of CF is in my humble opinion not satisfactory (and rather a mess). I even think that some fundamental questions about consistency and viability are not sufficiently explored. What about overlapping, fragmentation, behaviour when ranges are filled ... How to get that in fashion? Furthermore the formula editor inside the manager is causing headache now and then ... Even if everything got clear we might need an extra 'Guide' of some 100 pages to explain it.
On the other hand CF is sometimes really a valuable means.
My suggestion: Use it with caution.
Introduce it late during the design of a new sheet.
If sheet editing is going on, call the CF-manager in not too long intervals. First delete cf ranges you don't need any longer, collect (not so easy), simplify and adjust in time - as long as you have still clear in mind what you wanted to achieve.
Two or three conditional formats should be enough for a sheet. Who should evaluate all the 'visibility' they create?
Wait for the perfect final solution.
You should have enough karma now. Please edit your question to include the screenshot. Thanks.
Image now uploaded, showing one conditional rule set that has been fractured into many rule sets. Note that some ranges shown above would make contiguous rectangles, if they were normalised. The original cell range was A3:B1048576. This problem occurs in 4.1.6 and 4.2.5.