Should I ask laboratory students how much time they spend there?

Yes. To understand the laboratory’s actual working pattern, you can politely ask students, “How many days or hours do you usually stay each week?”, “When are the busiest periods?”, and “Are there rules or expectations about how long students stay?” Do not judge the laboratory from one student’s experience alone; ask several students and faculty, and consider differences by course workload, research topic, and year. Check the university, faculty, and laboratory’s official information as well.