My personal experience:
As an Engineering Manager for multiple Engineers for decades, two key experiences stand out. The first “Heads Up” on marijuana came from a new Stanford graduate. He initially started into the Engineering program with eight personal friends from their dorm. Initially as Freshmen, then more so as Sophomores, they all tried some pot in varying degrees. This individual didn’t like the “dullness” he experienced for some time after smoking and stopped using. Some of the eight indulged more than the others did. They were the first to drop out of Engineering because they couldn’t comprehend the correlations of the math, the physics, or basically the logical cause and effect of nature. Their falling grades forced them to change majors into things like Psychology, Political Science, History, or other “non-exact” disciplines that don’t require as much factual correlation or logic. Some “hard users” dropped out of college altogether. By the end of the Junior year, he was the only Engineering major left of the original eight.
The second is my own experience... I’m obviously a “light weight.” I tried it when I was 42, just divorced, and looking to rejoin the “social scene.” After a couple of tokes, I was impaired at performing most any critical thinking, or anything that required one to be alert and quick in physical responses. Just zoning out and relaxing was the basic thing to do. I also found that for days later I could not stay focused, reasonably correlate data, or make good decisions in my work. At the time I was heading up 12 R&D projects for United Technologies. The impact on my leadership abilities was very negative. Needless to say, I abandoned marijuana altogether.
I later found out that the half-life of the active drug in marijuana is 14 DAYS. Compare that to the half-life of alcohol, which is approximately 14 HOURS.
From my personal observance of multiple colleagues over the past 35 years that used pot, their learning abilities seemed to just plateau... they could not seem to accumulate knowledge, then correlate new experiences or data input and either solve problems or create new ideas based on those correlations. In short, they were noticeably mentally impaired.
Please consider these experiences and the possible impacts of any recreational drug use if you are faced with peer pressure to indulge.