There really isn't much to understand. The sbi bot will upvote your posts for the lifetime of your account. Depending on how many SBI you have, it may be every single post you make, or it may only be every second or third post you make. The more SBI you have, the more the bot upvotes you for.

Don't know if I can really clarify it much more than that, but feel free to DM me at dbooster#6252