I use frequency 55 toric disposable contacts (for astigmitism). They are supposed to be changed every 2 weeks. Many doctors will tell you that 4 weeks is ok. That being said, I use clear care contact solution (soft contacts), this stuff is freaking awesome. I always loved the feeling of new contacts and with this solution they feel better then new everytime. I have had many people try it and no one has ever not switched to it after using it.
here is a link for it (they sell it everywhere), you have to follow directions and be sure to change the holder before it runs out.
http://www.clearcaresolution.com/
Using this solution I will wear a pair of contacts for way longer than I should, probably more than 3 months! With all other solutions I used, I could never wear a pair more than 4 weeks and after 1 week I noticed degraded performance. I think this is the only reason I wear them longer than recommended, I only started on clear care around 2002, so from 1991-2002 I was very used to feeling what contacts felt like after 2-4 weeks with old solution and since I never feel any irritation, i figure they are fine.
If I had not found this solution, I would likely have done laser eye surgery.
That being said, I know a lot of people that are super happy with the results of laser eye surgery, you just have to make sure you go to the right place.
So, a brief answer to your question is that it is fine either way and I would not change pairs after every session. Kiting and water sports have played no role in when I change my contacts with clear care. With my old solutions it would cause me to change them more often because they did not clean the lens as much.
Hope this helps!