Shortly after the first shift your girlfriend of 5 years dumped you. She crushed your heart and you've decided to never trust anyone else with your feeling again.
Still craving the sweet embrace of a woman, you decided to become your own woman with help from the shift. You started tracking occurrences of the shift and found a pattern to their appearances.
During that time you also found out about merging and were ecstatic, your original plan had you repetitively visiting shift locations until you found yourself in a desirable body. With merging you could instead "build" your own provided you had a source of hot babes.
The only issue would be keeping your individuality, luckily you found a solution to that too in a small article about a nurse who got caught up in the shift while caring for a brain dead patient. Apparently the two merged into one person but there was no noticeable traces of her patients mind.
You've predicted that a shift will happen in this town where there just so happens to be a modeling agency. From the dark web, you've bought a modified stun gun capable of completely frying a person's brain and hired a hacker to get you access to the facilities and book all the girls for a photo shoot today.