Well the low power reserve first time was obviously because the watch was not fully wound. I wouldn't be concerned about 69 hours - you still don't know if the watch was fully wound - try it with 100 winds, and even if it was the reserve will reduce as the watch ages due to the aging of the oils and the wear on the mainspring - 69 vs. 70 for a non new watch is not an issue.

For the time loss with low power reserve, it's inaccurate to say that a watch "should" gain on low power reserve. All other factors being equal a watch with a low power reserve will gain because the amplitude will drop and the frequency will therefore increase. In the real world there are numerous things that might impact that - friction in the running train is an obvious one that might well show up with the reduced torque that results from a low power reserve, again symptomatic of a watch that is no longer brand new.

Watches don't operate identically for 5 years or so and then suddenly require servicing, they age over time until the degradation of mainspring, hairspring, lubrication, etc reaches a point where the performance under everyday situations makes a service necessary. By observing the watches at the extremes of the reserve you are simply seeing those symptoms earlier than you would through normal wear.

Roff sorry check with you, technically as a watch ages with time do we need to wind more times in order to fully wind a watch?

Well the low power reserve first time was obviously because the watch was not fully wound. I wouldn't be concerned about 69 hours - you still don't know if the watch was fully wound - try it with 100 winds, and even if it was the reserve will reduce as the watch ages due to the aging of the oils and the wear on the mainspring - 69 vs. 70 for a non new watch is not an issue.

For the time loss with low power reserve, it's inaccurate to say that a watch "should" gain on low power reserve. All other factors being equal a watch with a low power reserve will gain because the amplitude will drop and the frequency will therefore increase. In the real world there are numerous things that might impact that - friction in the running train is an obvious one that might well show up with the reduced torque that results from a low power reserve, again symptomatic of a watch that is no longer brand new.

Watches don't operate identically for 5 years or so and then suddenly require servicing, they age over time until the degradation of mainspring, hairspring, lubrication, etc reaches a point where the performance under everyday situations makes a service necessary. By observing the watches at the extremes of the reserve you are simply seeing those symptoms earlier than you would through normal wear.