Is it really necessary to restate information that could be months, if not years old? By restating that a user trusts/distrusts another user all you are doing is filling your own logfiles with endless pages of repetitive information.
Surely stating a person has been made, or removed from, DT1 should be enough information, otherwise it's going to appear as though DT1 users can't make up their minds repeatedly trusting/distrusting when in fact it didn't happen.
Assuming you are referring to the DT1 lottery/shuffle each month and the repetitive entries that occur because of it, those repetitive entries are not intentional, they are more of a side effect on how the parser is currently reading changes to DT1 inclusion/exclusion lists. I'm hopeful this will get cleaned up at some point, assuming we find a good way to isolate those monthly changes to either identify & condense them.. or maybe hide them?.. but no, those particular repetitive entries each month are not necessary.
I do think the historical reference of DT1 trust changes can be relevant, so I think it still makes sense to save the history, in general.