Sure, if you go downwind in five knots of wind.
Otherwise, the tension of the stays is usually determined by a number of factors, primary among them the type of mast you have, the diameter of the stays and shrouds, the "rake" of the mast, and the type of sailing you do.
Most stays are too slack, i.e. the rig is not optimally tuned. This can be seen on each tack, where the lee shrouds are slack. Too much slack leads to too much mast movement, work hardening, wear and crappy sail performance: The stays are the "ligaments" of the rig, with the mast, hull and chainplates forming the "skeleton" which transfers the power of the wind in the sails to move the boat. Slack stays=poor transfer, wear and eventually failure.
Consider borrowing or buying a Loos or other type of tension gauge, and determine the usual rig tensioning for your boat. Check all chainplates FIRST, because you want to ensure that the reason the stays are loose in the first place is because the chainplates are half pulled apart.
Ask for help. It's not an amateur job, but it's one easily learned and the results may surprise you.
Rigging Tension: Information from Answers.com