I believe a better and faster way to build a "free" bankroll is this:
Research the best way to start a new account at any site (sign up bonus, new player freerolls, affiliate freerolls,
rakeback, etc.). Deposit a reasonable amount that you are quite sure you can clear the matching sign up bonus in the alloted time. Participate in any new player freerolls, affiliate freerolls, and other promotions being offerred while you clear your sign up bonus.
Most of the sites allow 3 to 4 months to clear the sign up bonus. Play within your bankroll. Convert all of your points, rakeback and bonus back into your bankroll. Withdraw your original deposit once the sign up bonus has cleared. Going forward, only make deposits when reload offers are available and always withdraw your deposit once it has cleared.
Comparison to building exclusively through freerolls:
Advantages: 1. play when you want
2. play the games/levels that fit your style/bankroll
3. sign up bonus "cushion" and other "freebies"
4. freerolls still available
5. more realistic poker play
Disadvantages: 1. must make deposit for sign up bonus - need $
2. may lose deposit before clearing bonus
If you lose your deposit before clearing the sign up bonus, you probabaly need to go back to the play money tables/freerolls to work on your game. Once you feel you are a better player you can retry again at another site, and pay yourself back your lost deposit if things work out.
I have used this "system" on 4 different sites and have built a bankroll of $500. to $2000. on all of them. One advantage of playing on four different sites is you can participate in their different promotions and clear reloads at different times. - never boring. One disadvantage is, if I played all of my poker on one site I would be higher in their points system and receive more perks.