Ok maybe is not right answer on your desire to answer you some "140+ lvl witch" more but I can give you some good tips abt shortcut bars...
I got:
1 PvE bar
1 Self Buffs and pets bar
1 PvP bar
Most important for me is to most used skills and items for... for example: healing... is to put them on quickest keys on my shortcut bar. Ultra Quickest keys for me are F1,F4, F5 then less quickest (hand finger need to move longer distance) are F8 and F9.
F1, F2, F3, F4 and F5 I press like I'm "playing piano".
Hardest to hit right... for me... are keys F7 and F8 (hardest to find them quick and press right on them without missclicks!)
F10 and F11 I use for skills or other icons which I using but not so often.
F12 is easy to press and always hit it good (without missclicks) but it's longest time for hand finger to go and press it.
So after all my hottest keys are: F1, F2, F3, F4, F5, F7, F8, F9 then F12 then F10, F11 and F6 is last cause it's hardest to find it in "middle" of shorcut bar.
Point is that you can press them fast and without missclicking.
To know which skills to put where it depends of knowing your skills effect, cast speed-animation, refreshing speed, power/damage, amount of MP etc. It depends of your play style and what situation you got in game.
I got no "fixed" and "final combination" shortcut bars and I tweak them sometimes on every special occasion in game/situation to be fast and effective as possible.
Best is: to know your skills as witch, know your playstyle and to be fast in pressing right keys.

Guild: RANGERSOFJUSTICE, Guild Advisor IGN: Gospodja - 4th real Witch on Katar