What is "target decision date" in sciencedirect-publishing journal? According to the information retrieved from EVISE supporting agent, my revised submission was undergoing the second round of review. I have found out that both referees missed their target deadline (without any request for further extension).

The agent also tried to persuade that the submission will have final decision soon; (s)he called it as 'Target decision date'.

Here are the questions I would like to know:
1) Is it common that the reviewers returns their comments late?
2) Have anyone experienced 'Target decision date'?

Kindly regards,
Unfortunately it is all too common for some reviewers to be delinquent in their manuscript returns. In particular in traditional academic publishers. Often reviewers are professors/researchers with multiple hats in academia including writing up their own research.  I would agree with the previous answer that a target decision date is a way for editors to try and push all reviewers to respond. 

One example where the turnover is quick(er) is the highly structure online journals like Frontier or PLOS. In the former the turnover is ±14 days for most journals and article submission. The second review process is also around 14 days so all in all about 5-6 week turnaround depending on the quality of the manuscript.