Re the needle in the hay stack.
If at all possible flight plan to an easily identifiable position, even if it is slightly off track, however still close to your needle, which will give you a short leg to the needle.
Navigating over a short leg should make it alot easier to find your needle, especially at low level..
Maybe give us a scenario and we can offer some suggestions.
As for 10 mile 10 min etc I beieve it depends on the type of terrain you are flying over.
I prefer 10nm markers myself, however they are at their most uselful over terrain with regular features.
Over feature less terrain you might find proportional markers more use. i.e. 1/2 1/3 etc.