I'd advise taking all 'literature' and 'reviews' of breed characteristics with many grains of salt.
Different lines of breeds can have different characteristics, different individuals can have different characteristics.
 
My Wellie pair, acquired as 1-2 week olds and handled frequently while young in brooder are both pretty mellow.
 
The cock has marvelous temperament, but I stopped handling him frequently at about 6-8 weeks....
.....just enough to remind him that I would handle him if I wanted and he wouldn't die as a result.
He keeps clear of me when I'min coop or run, has some concerns when I handle hens/pullets but never shows any aggression to me. 
The hen is a bit of a bully to the other birds, is a lousy layer, but is not overtly skittish.
 
I rarely handle my birds during the day, I just don't want to chase a bird down to catch it, both for my sake and theirs.
Taking them off the roost at night for inspections and/or treatments is so much easier for all concerned.
Chickens are just skittish prey animals, they can also become annoyingly 'aggressive' food seekers.
Depends on your goals, and their individual temperaments, how you handle them.