I prefer to mix and it really helps with PIP when you can dilute a higher mg/mL concentration.

If I have to much loaded ina syringe I I just shot half the syringe then switch heads and finish the remaining volume in the syringe.

I always load everything together unless its waterbased with oilbase. Roll the syringe do not shake to mix them together

I mix and match up to 3 ml in the same pin. To me it’s better to only burn one site and only risk one injection going south (ie infection) unless the volume is more than 3 ml. I don’t line putting more than 3 ml in one spot in the same shot so if I need 4 ml I will split 2 & 2.

I always mix everything’s together and never had any issues.

I don't understand why someone would separate provided that they are all oil-based (although there are those who even mix water-based and oil-based). As a chef, I sometimes put 3-4 different steroids in the same syringe. In my opinion, there are no flaws. Separating each steroid would be impractical and totally unnecessary.

It all comes down to if it causes PIP or not. I for one mix all of mine into the same syringe and my sources never give me PIP. I had Test E, Deca, Tren all in the same syringe and never had an issue. I do split it up to twice a week shots though.