Most second authors of sci have higher recognition of the first author and correspondent author when they are promoted to deputy senior titles. If your second author is also a correspondent, it can be used in the evaluation of deputy senior titles. On the contrary, it is very unlikely that others can use it. However, whether the second author of sci can be used for the promotion of associate senior titles mainly depends on how your unit evaluates the requirements of associate senior titles for evaluation papers. Because different regions and different disciplines have different specific requirements for commenting on deputy senior titles, it is not 100% certain that they are useful to the second author, nor can they be sure that they are useless, depending on the specific situation.