Hasta La Motion!

Hey people.. its been a while since i posted.. Well first thing is i want to thank all the people who helped me on all the questions that i posted as i got a job as a Roto-Artist..

Now.. moving to the question.. i read the Rotoscoping Techniques posted by Aruna for the 10 th time now and i have come up with a question.. Say for example if i wanted to rotoscope a cloth.. for example a waving flag… In a waving flag example.. it would be hard to maintain the spline points all through the shot where they were originally placed in the first frame right?? there would be a bumps or curls on the flag so it would be hard.. So in that case would be okay to defy the Rule which says

"try to keep the points steady and maintain them where they were originally placed in the first frame.."
thanks in advance.. looking forward to a reply..