DO GAME BONUSES BOOST YOUR WINNINGS OR JUST EXTEND PLAYTIME?

At online slots, playing for real money, one sees how bonuses in free spins and multipliers appear to be the easiest path to larger rewards. They are commonly advertised as a good way for extra money to come in, but do these features truly make the grade, or are they more of an entertainment tool to keep you spinning reels for a longer time? In