Bumping trash thread does not help you earn a single merit.
An other trick to rank up seems to be by bumping your own threads in Meta and Beginners boards.
You should read forum rules before commenting posts lite this.
I usually do not bump my thread each day, around 3-days per one bump, or even longer. There is nothing wrong about that, especially if thread owners bump their useful threads.
If it doesn't really help then why would you bump that thread?
I mean, people already ignored the topic because it wasn't good enough and maybe you didn't provide the information they're looking for. So there's no sense if you'll bump a trash thread.
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In my case, I always keep the discussion lively and give good statements that will encourage them to reply. So through that, the thread will automatically bump through the opinions or statements of other members than spamming
bump on the thread.