Considering you can boost an RAF team up to 60 in 8-9 hours /played if done right, I would go for as many groups as you can.

I personally had 5 accounts that I only boosted one team up on, letting the RAF expire. Now I have many other team ideas and can't deal with no RAF. Time = money for me, and boosting is work...so I'd rather it be quick and painless. I ended up buying 4 new alt accounts and trashed the old 4, starting on a brand new server and only bringing my main along to do the boosting. I could have only gone with 2 more accounts and transferred after boosting, but I want quite a few teams and it made more sense financially to completely start over

So far I've got a team of DK/4x Rets up to 60. Time to park them and continue with a 5x druid team, then possibly 5x rogues. If I'm still going and not burned out, maybe a backup shaman team.

I would recommend taking your time on the boosting. While I accomplished 1-60 in 10 hours on my first team, that translated into a week of time. I don't want to burn out, stop boosting, and 6 months down the road want to start over again. You can get quite a few teams up to 60 by playing a few hours here and there. 90 days is a long time, but not if you get burned out and stop after the first week