Though adhesives from different manufacturers can have similar performance levels and usages, the actual compositions can differ quite a bit. That, of course, affects what they can be used for, and in what manner.
Always read the instructions. All serious manufacturers test their products thouroghly before selling them, so that they don't get recalls and lose market share because of shoddy products. If you use any manufacturer's products in a way they didn't specifically state it was meant to be used, the liability is yours in case of failiure. Thus, the question on when to prime and not to prime, is moot, unless you develop the stuff
Here's a post I made on
primers recently.