After long refrigeration it’s almost impossible to get all of the goo out the bottle.
No amount of pre-shake is going to fix that.
If only this stuff came in a cup that is easy to scoop with a spoon :).
I’ve found that all the RTD’s have a ‘tipping point’ in the refrigerator where they get too cold and clump up like you say. these days I put them in the lower shelves or even salad drawer - so they stay cold but fluid. made the mistake once of putting them on the very top shelf and then had to leave them out a day to ‘loosen up’ 
My 1st chocolate rtd I put in the fridge and didn’t open it for months. When I got round to drinking it it was so thick and creamy it would hardly come out of the bottle but I really enjoyed it. My next bottle was only chilled overnight and was nowhere as thick as the 1st bottle and I felt a bit dissapointed. It also didn’t feel just so filling. So its just my preference to chill longer. I only use rtds occasionally as I still prefer the powder for portion control. 
