Totally. Each card is independent of the others. And they aren't tied to anyone either really. One card can get 3 FPs at TSM, and another three at RNRC. You can use the FPs however you wish.
We used our GAD FP's last week. We had 3 vouchers, so used them on 3 days. Since everyone in our party does not like the same attractions, we did tend to split them up, as above.
I do have a suggestion that relates this. If I were doing it again, I would carry a sharpie with me to keep track of the FP cards. It might not be hard to keep track of which cards were which if your whole party uses them for the same rides. But we tended to get them confused w/ each other, because they look identical, and we didn't always keep them seperate. If nothing else, I would write the initials of each member on their card if they will be used at different attractions. Then you know which card belongs to the person who has already used an extra Donald on RRC, for instance. We had only a ballpoint pen with us, and that wouldn't work on the cards.
The GAD FP cards worked great, though. At MK, Splash was on the list.
It was very cool to be able to get FP's at TSM after they reg. FP were gone (yes we had other guests asking why we could still get FP and they couldn't).
At Space MTN., all the FP machines were closed, and when my DD asked, they just gave her a handwritten pass, that didn't really use up one of her Donald credits.
Epcot was the only park where there was a wait to redeem the vouchers. Each park I redeemed them mid-morning, not before rope drop. I think you are supposed to have your whole party there for the voucher redemption. But you definitely need everyone's tickets. At MK, I asked if I needed the whole party or just their tickets, and I was told just their tickets. So they didn't have to wait with me.