Why repeated letters matter
Many of the trickiest spellings in English come down to repeated letters. Words like 'accommodate', 'embarrassment' and 'millennium' trip people up precisely because a letter is doubled where you might not expect it. Seeing the repeats laid out makes these words far easier to learn and remember.
Repeated letters also matter in word games and puzzles. Anagrams, crosswords and tile games all behave differently when letters repeat, and spotting the doubles quickly helps you plan better plays and solve clues faster.