Multiple axes:

• Degree of uncertainty and magnitude of duration of the length of time before it will be 'safe'.
• Degree of effort involved in avoidance (temporarily holding off on reading a specific email vs. actively avoiding certain knowledge and filtering all information for a long and unspecified duration).
• Severity of consequences (delayed or somewhat sub-standard performance on a near term project deadline vs. fundamental change or damage to your core values)
• Scope of filtering (avoiding detailed contents of a specific email with a known and clearly delineated area of significance vs. general avoidance of whole areas of knowledge where you may not even have a good idea of what knowledge you may be missing out on).
• Mental resources emphasized (short term attentional resources vs. deeply considered core beliefs and modes of thought and high level knowledge and understanding).

That's part of it, and also how far into the future one thinks that might occur.

In my perception, the gap is less about certainty and more about timescale; I'd draw a line between "in a normal human lifetime" and "when I have a better brain" as the two qualitatively different timescales that you're talking about.