I'm sure mistakes of one type or the other are as likely to be made with manual calculations.. In fact, delving into the orange take-off charts for the big 'Buses is fraught with potential mistakes - more so actually at light weight because of the requirements regarding min control speed..
For example on the 330 if Vr was below Vmca then I recall we just had to add equal speeds to the V1 and Vr (I say recall - may be slightly mistaken) and make no change to the flex temp. However on 340 if speeds were too slow you'd have to reenter the charts at a lower flex temp that gave higher speeds associated with it... I saw plenty of mistakes made there
