cannot use proportionate lah.... it's like... if you want to
make something beautiful, you need time, patience and effort
mah....
of cos for some gals, you can go faster lah. you have to gauge for
yourself the pace the gal is comfortable with. if you see some
signs of withdrawal, then means you going too fast mah...
that said, it is better to go slow and then slowly build up the
pace to test where her limits are, than to go too fast and have her
withdraw, and THEN you have to put in effort to make up for that
lost distance.