The methodology used to date does not appear to have been a resounding success after 11 years so we know it has not worked thus far.
No other methodology has been attempted as far as one can tell so the efficacy of any untried methodology is unknown.
That is your opinion.
In my opinion the methodology used was successful in having Madeleine's case reviewed here and as we later found out in Portugal also. Enough missed evidence was found to fully justify reopening the case into her disappearance in both countries.
In my opinion without the very proactive campaigning of her parents on her behalf and their collaboration with the press that goal could never have been achieved.
I am aware of course that there are some who think looking for this missing child and perhaps finding out what happened to her is an expense too far and have denigrated all police activity on her behalf bar that which came to in my opinion, the wrong conclusion eleven years ago.
That is their privilege.
However it is my opinion that until the present investigation is concluded it is premature to sit in judgement on its success.