Would it be safe and advantageous for those in need to take Pineal Guardian along with Advanced Memory Formula, FocusIQ, Ceretrol, and RediMind, if affordable?

This is actually the case, that each has some unique aspects that would add to the whole, and even where overlapping there would be some additive and potential synergy through having the combinations at work. Keep in mind, humans do not yet know much about what levels of nutraceuticals might be safe, nor what levels might give the best benefits. Testing is extremely costly and not done as a rule for that reason, so it will take many, many years for fundamental knowledge to be acquired. There are a number of circumstances, often with particular individuals and not necessarily universally, where there is a particular need for very high concentrations of something because of their particular makeup, so it is often the case that more is better.