Hi Ashton
It's all about dialling in the temperatures and pressures for your set up in your studio. Air temperature, storage temperature, humidity, paper type, printer, accuracy of you heating element, and this is before you get to the individual products.
If you think of setting up any other business and compare setting up a sublimation business, sublimation is very cheap. Wasting a few items is nothing.
There is a lot of information on here that will help you get in a general ball park, after that you "tweak to you".
Eg. A mug isn't a mug. Each manufacturer is different, each coating is different.
Reduce the variables. Find t-shirt / mug / Totebag etc that you like. Once you have done that only buy those items from that supplier.
Now change just one variable until you find a sweet spot. Let's assume temperature. Does the print look good? Could it be better?
If you think it could be better, now tweak time but do not touch the temperature. Where is you sweet spot? Then change pressure etc.
I have been known to use a full box of mugs to "tweak to me", only to come to the conclusion the mugs were at fault! Hence back to my preferred supplier / mug.
I agree about recommended times and temperatures. I have never been close to them. But hey we have to start somewhere.
Hope that helps.
Martin