Oh, helloes! Not been browsing the forum for a long while. Thanks for looking
The process is simple, I put K-1 to interval composite mode and selected average as the method. Then I just entered 600 images as the amount and let the camera to do its job. There seems to be some kind of issue with internal precision with large amount of averaged images. Anything over 256 images is more likely to result in this kind of outcome instead of natural colors IF the images have lot of bright parts in them and have proper base exposure set. Sometimes the averaging however works with huge number of images. I did some 1024x averaged composites with Pentax KP with no issues.
Shutter takes the hit of course if someone is worried about shutter life. I wonder why Pentax did not allow fully electronic exposures with the composite mode. For sure it can be used as pixel shfit already does that.