Ayumi's Singles: CD or CD/DVD Combo Pack?

[AyusakiFan]

Hello. For those of you who buy her singles, do you usually buy her single disc or CD/DVD combos? I'm usually the type of person who strictly buys the CD/DVD combos whether it's the single or full length album but I was reading someone's post in another thread about how all of the items on her single DVDs end up on her full length album. So is this always the case or are there videos on the singles that don't always make it to the full album?