There's this principle, which is good to apply when you can; and then there's the principle of choosing your audience. If you explain a fact in plain language in one sentence, you will miss some percentage of skimmers. If you bring it up four times, you will catch more skimmers and lose anyone who wants a faster pace and less repetition. Similar balances hold for what things do and do not cost suspension of disbelief. If you obey the reader who finds Randi to be a challenge to that suspension, then you weaken your hold on the reader who thought the original version of the tidbit was charming, and has never heard of this replacement fellow. And the reader who disapproves of excessive editing after the fact.