Absoluely. You need a decent bankroll to even bother with these. If not, another option is to look for deals on Betfair (they have run this promo previously) where you pick a player and every time he scores you'll be given a £2 free bet. Easy to lay off and extract £1.50+ from. Soon makes up for the stake on the longer lines.

Of course, don't pick someone like Lallana because you'll get nothing...