These things were always why I hated group projects though, because even if I didn't do any activities the other persons could impact us being able to do something. If I did a reasonable amount that wasn't too much (even one thing) the chances of that are even higher, espeically if someone is going away for the weekend. So even cutting back on activities may not help. Espeically if you got stuck being paired with someone that had uncooperative parents or ones that had transportation issues. Most of the time I just ended up doing the entire project and claiming they helped because it was easier then dealing with that AND wondering if the other kid would do decent work. I specifically when we could pick partners tried to pick the slackers just because I knew they would allow me to do this.
In college it was a bit better because most of us at least lived on campus and you had the option of meeting later at night because its not like college students really have bedtimes. People always claim these issues teach you how to work things out in real life but it really doesn't.
If I had a coworker that did no work and didn't respond to my inquiries trying to work with them, my response would be to go to their boss and explain the issues. If it was because they had too much other stuff their boss would be expected to deconflict that. If they just weren't working they would be told they would be facing disicplinary action for not doing it. I have had to do this in the past. However most instructors don't want to deal with it and tell the kids to just work it out themselves which is bull.
Also at work everyone is expected to be here for the same 6.5 hours of core time (we can flex around that) so there is a much higher chance of schedules aligning.
People always claimed these things were to prepare us for work but frankly work is 1000 times easier then what we put kids through.