Pinky fingering question

[ajd]

Hi,
I have recently started learning flute and getting along fine but I have an issue that I can’t figure out for myself and haven’t found any comments on this elsewhere.
Fingering charts show that when playing all the notes except low C, C# or D, the pinky or the right hand should be on the D# key. I can see that this stabilizes the flute in the hands somewhat and has no adverse affect on the notes, however I do find it tricky to keep moving the pinky on and off the D# every time a go past a D note at speed. Is the pinky supposed to remain pressing on the key when playing all note except the D, C# and C or can this be omitted when playing faster passages? Furthermore, my pinky’s middle joint seems to lock and I cant move it fast enough but I have a feeling that is just a matter of practice and strengthening the finger.

Thanks for your help.