I would go broke replacing chains every 1,000 miles! Properly maintained a chain will last many thousands of miles. Simply get out your chain gage and check it. Better yet, use a 12-inch quality steel ruler. When using a ruler place the end of the ruler centered over a pin. A new chain will be exactly 12 inches to the center of the pin 24 links away. The technical limit is 1/8 of and inch past 12 inches for 24 links. In order to keep my cogs and chain rings in good condition I replace the chain at 1/16 of an inch. Most chain gages have two sides, one for half worn at 1/16" stretch and second at 1/8" stretch which indicates completely worn out. Don't check only one part of the chain with a gage or ruler. Check several sections as chain can have differing worn areas. If I were going on a long tour in a far away place and my chain was stretched pass 1/16" I would go ahead and put a new chain AND cassette on the bike. Most reputable mechanics will tell you that chain and cassettes should be replaced at the same time but using 1/16" as the replacement limit will allow you to get away with reusing an old cassette or freewheel.