I pencil/score on crosscuts and rips, not end grain. If the circular saw is in my hand, I cut to the line if possible, if the chain mortiser is in my hand, I cut to the line if possible... I only cut to the line with the chain saw when squaring the timber off to finished length, or if I feel a bit crazy(not too often)
I don't think scoring is that much slower if you know your layout.