Few questions about anal!

Hi guys , Just a few questions , so the back story is I've had anal 2 times with my partner now , it was great but he has to take viagra to keep it up as it takes a while for me to be able to get him all the way in without him going soft , Will this get easier to go in quicker the more we do it? Is 2 times a week a good number of times to do it? Thank you