In very light air sailing close hauled into the wind the traveler is usually brought to windward and when the winds stiffens, it is let down to leeward gradually. In puffs, you can release the traveler instead of the mainsheet. In heavy winds where you want flat sails, you usually have the vang on hard, but if you get into a broaching situation, you need to release the vang right away. Off the wind on a broad reach the traveler controls the twist in the leach of the sail. Ease the traveler and you get twist, which opens up the roach. Tighten the traveler and you straighten out the trailing edge of the sail which decreases twist.
Travelers on Catalina 22's were on the transom and earlier models weren't very long or sophisticated, so you are limited with the range and use of other travelers mounted further forward and longer in length where the effective range increases.