I think secret ballots are ridiculous. While it's true that based on current publicly viewable votes can influence/sway a person's casting, it doesn't stop campaigns and pressure from happening behind the scenes and in the open. Manson was notorious for doing that crap in TRR, which is both preferential and public. Despite that, it did make it easy to follow who was voting what that weren't being swayed by only viewing already casted votes/the numbers.

Now moving onto the topic, I'm not entirely sure about this. I don't think it will change anything either. On one hand I find it reasonable to have one vote only, but it also limits choice to changing minds. Personally, I have almost never changed my vote unless it was for reasons such as someone withdrawing from a race or for some illegality of the candidate (though under preferential voting this isn't much an issue since those votes can just be ignored in the case of those two reasons). So while I have no issue with it, I still don't think it will solve anything which then means it's unnecessarily blocking people from changing their minds for any reason.

Manson didn't need people to change their votes in order to vote stack and heavy handedly sway elections. Where he was most successful was canvassing inactive citizens or nooby citizens that didn't know better, and just outright asking literally everyone that existed to vote one way. While I can't say he was always successful, it did lead to mass participation of voters and very close elections every time. Which in this case though it wasn't very competitive despite such.