Without wishing to sound like a complete apologist for Manning, I do believe it works both ways.
Manning can only work their magic if you take responsibility for your own career and give them frank and sensible options. Simply saying I want to be CR, then QWI, then promotion into a Flt Cdrs post and subsequent Staff tour is at best ambiguous and doesn't emphasise what your priorities are with regards to location, ac type etc.
Similarly, saying I want Typhoons or I'm PVRing leaves Manning with no leeway to find any alternatives that you may have overlooked or never before considered.
However, giving Manning realistic and attainable options with a sensible time frame is more likely to yield mutually acceptable results - I'd like to do a Co, then Captains tour on the same ac but I'm open to a QFI tour if there's no Captain slots. Ground tour-wise, I'd rather not, but if its service need then I'd rather remain in the south of the UK within a Cmd or 2 Gp Staff appointment and look towards promotion or switching to another multi type within 3yrs.
Apart from a couple of years of 'Service Need', I'm happily on my fourth flying tour in my 3rd frontline type and Manning know where I want to go next and when. I stay open minded to my poster but they also know where my heart lies.
I suppose my point is that you can't whinge at Manning for not managing your career if you don't have an idea of what you want for yourself.