A case study on optimizing battery power consumption for CC2538 but can also apply for nRF52 based device - https://medium.com/jumperiot/power-optimization-from-3-to-7-months-on-a-single-charge-56de0c30f062.
Power Profiler Kit which is quite a good (for it's price) tool to measure the current is also worth mentioning. Also... Achieving 3-7 months battery (coin cell) life for some standard periodic measurement on nRF5x is not really a challange :?
Look like the device mentioned in the article is based on CC2538 and not nRF52?