I started the test with a 3 LR6/AA battery pack serving as power source on 2/24/2016 (see 4th IoT Button entry). The test was finalized on 03/04/2016 more or less the same time so I got a run-time for the battery discharge of about 9 days as expected. You can verify the raw data at IFTTT_Maker_btn_pressed and IFTTT_Maker_btn_pressed (1).
This means that the IoT Button can be in operation over a long time as explained in 2nd entry for the IoT Button. Each other IoT Node can work comparable if there are only a few connections to the WLAN router a day.
I have planned to repeat this test scenario to get better proven data from this experiment.