Content is rather minimal in my opinion, it all depends on how you schedule your clients and also your packages, for example, if you're going to poll your clients on an hourly basis of course you're going to have a lot more data moving back and forward between the sites however if you schedule them every one-three days than not so much. We also enable throttling during the day so basically it runs at 25% between work hours and then 100% after hours, this helps minimise your bandwidth. You should also remember that SMS/SCCM uses Bits to control bandwidth so this also helps keep things running smoothly. We're relatively small company with just over 1000 systems spread out across 10 sites throughout New Zealand, we only use one primary SMS Server all the rest are child sites acting as Client Access Points, Distribution Points and Management Points, with all the above mentioned in place we haven't been affected by any bandwidth issues to date (knock on wood).
Hope that helps.
Cheers