I recently received this question last week during a training session…
If I make a good part without injection profiling, but later, another employee later uses injection profiling to make the same part should that be the new standard?
If you can make acceptable parts with one injection velocity, then you should continue using one injection velocity. Each time you introduce another injection velocity to your profile, you increase the overall complexity of the system. This creates an addition point in the process where variability can be introduced as well as more potential for process tampering.
The goal of a processor is to establish a process using a straightforward systematic approach to setting each process parameter. If one profile can do the job correctly, there is no need to add a second velocity since the additional complexity can not be easily justified.