some background: i have never understood people who try to burn shitloads of items before upgrading something important, but as so many ppl do it, i thought why not check it out, if its true, maybe it can be used to make some extra money off the anvil.
in theory, any toss of a coin is not affected by the ones who preceeded it. for instance, if i toss a coin 100 times, and the first 99 times i get heads, the 100th time i toss the coin still has 50/50 chance of heads/tails. now the anvil is no ordinary coin toss, but the same principles of statistics still apply (including the above law of indepedency between two random occurences).
to test this, i have made alot of high class upgrades which i kept track of to figure out if there is any dependency between one upgrade and the next. here are my findings:
success rate of upgrading high class items from +2 to +3 with high class upgrade scroll is: 60% (60 out of 100 items went from +2 to +3 and 40 burned).
success rate after a failed upgrade of high class items from +2 to +3 with high class upgrade scroll is: 65% - 26 out of 40 items went from +2 to +3.
success rate after a successful upgrade of high class items from +2 to +3 with high class upgrade scroll is: 60% (stays the same) - 36 out of 60 went from +2 to +3.
i made about 100 upgrades overall so to make this data as accurate as possible.
the upgrades were made on cw2 when no one else used the anvil.
this data goes to show that there is little dependency between one upgrade and the next (although there was a slightly increased chance of a successful upgrade after a failed one).
i would love to see more ppl post here success rates of other upgrades (like +4 to +5 with bus, or +6 to +7 with trina), so everyone could benefit and manage risk taking with the anvil wisely. please post success rates that you tested and not what you think the success rates are.
also if someone still thinks that you should always burn shitloads of items before upgrading something important, i would love to hear why you think that, and if it ever worked for you.