>> To call the tefilah for parnassah a segulah is misleading. Saying it today is no different than saying it yesterday or tomorrow. It may be nice to say it today if you need it, but then say it every day.<<
There is such a thing as an Eis Ratzon. A time where certain types of tefillos are more powerful. There is a beautiful tfilla from the Shlah HaKaddosh about raising children. It can be said whenever you wish, but there is a speciall Inyan to say it Yom Kippur Katan for Sivan.
>>Many “segulos” come from pagan and other non-Jewish sources, and they are worthless at best.<<
No argument here, but why passul the real segulas because of this? We see in Parshas VaYetzei that the Dudaim had the power to assist in becoming pregnant, so much so that Leah and Rochel fought over them! (And have a look at the Rabeinu Bechaye who says that It is rubies, and it still works for someone who has fertility issues or trouble giving birth). Is it automatic? hardy. Can it work without tfillos? doubt it.
But all sgulos are worthless? There are Mishnayos, Gmorros, Rishonim and others who humbly disagree with your opinion