Suppletive forms break normal word-creating patterns, which can confuse language learners. You can't predict 'went' from 'go'; it's a suppletive form.
Pro Tip 2/3
Historical Roots
Suppletive forms often arise from historical language evolution and mixing. 'Went' is the suppletive past of 'go', originating from an entirely different verb.
Pro Tip 3/3
Limited Use
Suppletive pairs are rare and usually limited to commonly used verbs or adjectives. Because they're rare, identifying a suppletive pair like 'go' and 'went' is tricky.