If fellow members only tell you what is good about a piece, it is unlikely that your skills will improve. Please turn in only completed work that has been proofread. If the group is kept busy correcting silly errors that could have been caught by you, it is unlikely that more serious or subtle problems will be found. Please don't expect more than about 30 pages to be read per meeting. Short stories should always be turned in complete no matter the length.
Rule of thumb is to turn in two chapters of a novel at a time.
Earlier critiques may help with revisions of later material that hasn't been seen yet. The first read is important. The group is coming to the material fresh and without expectations. Later reads will be colored by foreknowledge no matter how hard we try to put that information aside.