arrrrgh... I can sort of see what you are talking about without actually seeing it... so it is diminishing when it is a time step of one which would suggest that it would be persistent over the time step of 3 but diminishing at the same time... so I would agree. Aggregation either over time or space is going to hide anything that may be a pattern. Conversely, too detailed in either/both can have the same affect. Since you have the data at the 1 year period, I would not aggregate as a step in describing trends, but to summarize over a period.
To confuse things more, ArcGIS PRO seems to have a better description and options for similar analyses in their help
Emerging Hot Spot Analysis—ArcGIS Help | ArcGIS for Desktop
and I can't quite find the equivalent in ArcMap, but that may reflect the differences in the capabilities.
I haven't gotten around to visualizing it using time-slider capabilities yet either
This help topic says use ArcGlobe or ArcGIS Pro to actually 'see' what is going on
Visualize Space Time Cube in 3D—Help | ArcGIS for Desktop
so if you have either, then here is the methodology
Visualizing the Space Time Cube—ArcGIS Help | ArcGIS for Desktop
Which is in essence, old school overlay mapping with transparent overlays.
