From my own experience and working with others, I have seen that it takes about half as long as you have had symptoms because the longer this goes untreated the more totally infested an environment becomes. This means it takes longer to get clear due to re-infecting yourself with things you forget to treat or miss and because of that, reintroduce the bug and infect your environment all over again.

Getting over it is not what takes the time; it is starting over because of mistakes.

A cluttered house of course is the most challenging.