allocation percentage convergence
to keep in short: No. As far as i know, the percentages are the probabilities for a user being assigned to a bucket. This assignment has no memory regarding other users.
But keep in mind that changing allocation values might have an undesired influence on your results. Whenever changing them it is a good idea to copy your experiment and starrt the new one, as long as you do not fear to confuse a larger set of users by showing them something new.
"the essence of the creative act is to see the familiar as strange." (anonymous)
It is not a good idea to put 100% of the experimental units to Bucket B for a paricular time peirod, which means that something happen during that time period could become very influential for the results, and there would be no way to tease it out.