It totally depends on the snake, it seems... some snakes might be easily stressed out with handling. But many are totally fine with handling every day for 30 minutes even.
I handle mine every day for some 20~30 minutes, or up to an hour, depending on what I feel like... they really don't mind. And I don't handle the 2 days right after a feeding. Cake (around 500g) eats every 9 days, and Yukon (250g) eats every 7 days.'
I find that with handling every day, mine become MORE tolerant/trusting, and mostly just sit in my hand/arms and look around. They move around a little, but always come back to my hand, even if they have a choice to leave.