The 10% cap rule is only applied once per hour when the median feed is recalculated (at which point, if necessary, an upward adjustment is applied to the median feed value). In between those updates, there may be some intermediate results that aren't fully up to date. Does that answer your question?

Bear in mind that any time you initiate a conversion the conversion rate won't calculated and applied until 3.5 days later. So you are always guessing to an extent what that future rate will be. Of course, knowing how the rules work may inform that guess.