SP can be pretty consistent for each person, where you know what to expect, what hallucinations you usually have or don't have. But there are some occasions where, for whatever reason, the hallucinations are different or more powerful. I know I've also had a few WILDs where the SP is different than usual, probably has something to do with what the subconscious mind is thinking, or you're just entering a very vivid REM stage due to when you went to bed/when you did your WILD/what you ate before bed/what you did that day. Everything effects our sleep and probably SP as well.