The lifters will expand from the oil pressure after start up is this not correct? That is the purpose of them in the first place, and that's how they self adjust. That being said installing a lifter collapsed and not pumped up will actually make it grow in length, not by much but enough to warrent a valve adjustment and possibly enough to keep the engine from running via keeping the valve off the seat.
Also the oil supply from the lifters goes to the lifters first (filling them and pumping them up) then out rhe top of said lifter through the push rod and then to the top end lubing the rocker arms and cooling the springs.
Ive always pumped up my lifters with them installed using a oil priming tool taken them to 0 lash then + 1/2-3/4 turns and seldom need to fiddle with them past that
That is what I have always done and the theory behind it can some one enlighten me if I have offered poor advice
If I had a new set of lifters and 6 were collapsed or hung up out of the box I would be weary of there quality and would remedy that issue first. What brand are they? The spring inside should not of let them collapse from being in a box I am suspect of there quality