That is how we've had to do a good proportion of them. Theres at least 300 on the job and a reasonable percentage of them, possibly half can be done trad off a ladder, which is the quickest way considering how bad they are; not having been done for a year or more.
Saying that I'd say 75-100 we've done over the balustrade as you've suggested and the others from the ground with a pole, but the weather isn't helping. It's a case of practise and practise some more to get up to speed and competent. One thing that's made it a struggle is that the head on the end of the pole, which ever one we've been using won't lock in position, this would make things a lot easier as the brackets holding the glass in place restrict the effectiveness of what we do.