Frequency depends on the corpus
E is common in general English, but a word-game dictionary and a newspaper corpus have different distributions. Technical writing boosts letters in specialized terms; names change the picture again. Always ask what text was counted.
Position matters
A letter can be common overall but uncommon at a particular position. Q rarely ends an English word, while E frequently does. Five-letter puzzle strategy improves when you consider positional frequency rather than only the global E-T-A-O list.
Pairs carry more information
Knowing that H often follows T and that U often follows Q is more useful than knowing each letter’s individual rank. Digram and trigram frequencies capture spelling structure. They also explain why a rack with common letters can still be awkward if the letters do not combine.
Use frequency as a prior
Frequency suggests where to look first; it does not prove an answer. A clue, fixed pattern, or letter inventory outweighs a statistical preference. Good solvers combine frequency with hard constraints and expose the distinction to users.
Quick review
The strongest habit is to separate hard constraints—letter counts, length, fixed positions—from helpful clues such as frequency and familiar patterns. Use the tool to narrow possibilities, then use meaning and context to choose.