Jinky,
I only put the pointer on frames mate, but like we have both said it all depens on the job, every window is different and you have to use whatever method you think is right for the job in hand
David,
Get yourself a pointer mate they are worth it, make sure you take a good look at the job before you start and use jinkys an my advice, weigh up the situation and work out a plan of attack, dont rush you will be fine, try my tip of tapping your blade it works.
Good luck mate.