I have beguns to group my full questions under the problem rather than the specific phrase because it allows for cleaner pages and prevents key word cannibalisation.
In all honesty, I dont. It is more a matter of analyzing what people really input in search engines and then optimising for that long form language. Honesty is short keywords were what bring the real traffic.
The good thing is not that the query is long the gud thing is what the users add after the root word. the modifiers some times shows the true intention more accurately than volume does.