Are you trying to make $200 from $100 then $400 from $200 and do that 8 times? If so, then odds are the same as if you go with 8 parlay and put $100 on it...
However, if you are talking about systematic gambler, who has some kind of edge and appropriate investing plan, then it all depends on many parameters ... (It can be summed up as: how often does he guess a coin flip?, how many time will he play that bet?)
For example:
If he has 55% on coin flip bet odds (+100) then with Kelly staking single plays he'll need to play 140 bets to double up his starting capital.
On the other hand, if he has 65%, and plays 8 games at the same time (in system 3 out of 8, because that is most profitable to do with 65% average..) and invests for maximization, he will need only two described systems to double up. Of course there is variance to be accounted for, but that's another story..
Hope this helps a bit..