If you can set yourself up with a good target then Well Prepared is great!
With some XP in hand you can combo with Physical Training to become very strong in combat and resilient to treacheries, a thing can be said for Wild icon assets even if its just the single icon (Rabbit's Foot for example, many unique investigator and story assets would be incredibly powerful as well, or just the classic ol' Elder Sign Amulet.
To make Well Prepared worth it I think you need a deck with 3+ cards to reliably trigger 2+ icons off (or a wild icon), that will often mean that you're fine off with just Physical Training and 1+ unique/wild cards.
Update: Just to reinforce this review:
This is a fantastic card when you can get the multi-token triggers, but, it suffers from set-up issues Once the pieces are out, especially once you got multiples of this thing down, you can succeed on all kinds of checks with ease. The more cards that you can benefit from and the more draw power you have the better. Also, the more varied your valid targets are the better, if you play a character to who damage and horror tends to stick (reads: Most characters)) then your targets to trigger Well Prepared with might as well be Bulletproof Vest and/or Elder Sign Amulet, both of which have icons.
Zoey's Cross is a terrific target, an effective +3 is crazy and then there'S the icon.
Whichever of these character strengths you have, Physical Training is the perfect supplement to the build, aside from being a potential trigger for Well Prepared it also lets you bridge the gap to get maximum hit chance on important tests. Well Prepared is always ready to go during the mythos phase which means that you can tap Physical Training for +2 everytime you find yourself up against a crippling treachery.
As a capstone to this type of build I must bring up Ever Vigilant + Stick to the Plan, it shrinks the deck and makes finding everything easier and then it fuels you by granting extra resources and saving actions.