How Long is power reserve for Mechanical watches?

Normally, the power reserve for Automatic or manual watches around 38-50 hours. this info. is indciated on movement data for every movement.

it means when the movement is fully wound, the watch can run at least 38-50 hours. some movements can reach 60-72 hours. it would last the watch in running during weekend. from Friday night take off the watches from your wrist, then Monday morning wear it on your wrist before working, No need wind the watch or adjust the time. it still has the power for ticking and runs as accurate as usual.

Some watches with power reserve indicator, like the fuel of your car to show a rang from "Full" to "Empty". this display eliminate the guesswork of how long your watch need to be wound. That is good for Manual winding mechanical watch and full cover the movement by Watch Dial. if with skeleton design like Hangzhou Tourbillon movement, you can see the mainspring in tight or loose.

Below watch, with power reserve indicator, The Vacheron Constantin Fiftysix Day-Date features a power reserve indicator on the dial at six o'clock. Its automatic-winding movement has a power reserve about 40 hours. Vacheron Constantin, founded in 1755, is the oldest watch brand in continuous operation in the world.

Rolex and Tudor use the newer movement for new models which can run 70 hours when fully wound.

Most interesting thing, A. Lange & Söhne, the Lange 31 can run for 31 days (yes, 31 days, not 31 hours) And it features [a patented constant-force escapement that continuously delivers uniform torque". So that you do not wear this watch for a whole month, and it will still be good to go when fully wound (manually).