Good question... I'm not a big measurer - I tend to guestimate and to
fiddle with recipes to make them my own... but when I'm baking
something new I follow their recipe as well as I can, at least the
first time.

I had an interesting cookie experience this week - last week I made
the Nestle tollhouse cookies, following their recipe for the dough but
using butterscotch chips and those hersheys mini-coated kisses for the
chocolate chips. They came out very thin and VERY crispy and they were
wonderful, but very sweet... I made them again last night but I cut
the sugar down to one cup (instead of 1-1/2) and I added a little
extra baking powder because I measured the flour a little more
generously (and I used pecans, butterscotch chips, and semi-sweet
chips because the candy ones were finished). It was only a very small
change to the recipe but the end result was TOTALLY different! This
batch of cookies didn't spread on the trays, they rose instead, and
they came out a lot more 'cakey' than crisp. They still taste okay,
they're just not the same, and we liked the original recipe better...