Recent research has demonstrated that written corrective feedback (WCF) has a facilitative role in second language (L2) grammar accuracy improvement. However, most of the studies explored focused WCF which targeted a couple of predetermined errors using a one-time feedback session and they disregarded learner individual variations. The present study aimed to fill the gaps in the previous WCF research by investigating the role of unfocused WCF (i.e., targeting a range of errors) offered via multiple feedback sessions on grammar accuracy improvement, and learners’ individual differences in benefiting from WCF according to their language analytic ability (LAA). The study collected the data from four intact intermediate EFL classrooms at a university. Three classes were feedback groups, and each class received different types of WCF over six weeks: direct correction (DC), coded indirect correction (CIC), and underline indirect correction (UIC). The fourth group engaged in self-editing without WCF and served as a control group. Results showed that DC and CIC led to more improved accuracy than what was obtained from UIC and self-correction. In addition, the process whereby DC and CIC led to accuracy gains differed. Learners’ LAA was found to be strongly related to both DC and CIC while no relationship was found with UIC.