I’ve used all seven letters many a time and gotten like 14 points. On the other hand, I’ve spelled words like “the” and raked in the points. Strategy is important, but a good vocabulary will help you when your rack sucks.
I have a large vocabulary, but I overthink. In the heat of a game, I forget out to spell or I Verb a Noun or Noun a Verb. So I use the dictionary to help me save time by checking if something is legit. I mean, if I “played” the word, it’s going to tell me it’s not accepted anyway, so it saves a step.
I know my family “cheats”, but it doesn’t bother me as long as it’s not every word, every turn. Since I have a larger vocabulary and an usually better at strategy games, I figure it’s like a handicapping thing.