If they are players you want to keep, why would you risk losing 5 seasons of them to save some $ in one season? Even if they're 90% likely to resign, the risk would only be worth the reward if they are players you wouldn't mind losing. However common it is for them to sign, it wouldn't be common enough that I'd risk it with a player of more than marginal value. There's also a good chance their demands would increase next season, so long term you could be losing money while risking their loss.