I submitted a paper to an applied math journal in May 2015, and the first round review took a bit more than 7 months. I only received one referee report( usually two), which was generally positive. I submitted the revised draft in mid January 2016, and it is ``under review'' ever since. I inquired the status about 4 months ago and only got a reply from the journal staff, basically saying that my message has been forwarded to the handling editor (nth from the handling editor though). I am wondering if it is OK to inquiry again? Thanks for your input in advance. 

The suggested post is not exactly related to my question. I am aware of the typical workflow of journals. My question is more about, how long should I wait before I make an inquiry on a paper status (without being too pesty). This is actually field dependent and so I specified it is an applied math journal. To add more information, the journal states its target processing time from submission to final publication is 8-9 months, and it typically gives reviewers two months.