Generally, fewer but high quality / longer duration activities that you are committed to is better than a shotgun approach of lots of different things for short periods. It shows dedication / commitment and helps you write a cohesive narrative that can easily be seen by AdCom reviewing your application / history. I'd suggest 12-18 duration of clinical, 18 months research, and for non-clinical I think it's smart to commit to some organizations early and just do at a low-level consistently for 2-3 years (like just a few hours a month but steady). I'm just an applicant, but worked for me. I don't think there are necessarily hard and fast figures.
It's too variable for such generalized benchmarks. Some people get excellent clinical experience over the summers/breaks. Some do it longitudinally. Same applies for research and other activities. It just depends. For reference, I had 9 months of clinical employment, 6 months of hospital volunteering, and small bursts of shadowing throughout 3 years; many interviewers commented on how good my clinical experiences were because I wrote and spoke well about them. A friend of mine had clinical research over 1 summer, 1 summer of clinic volunteering, and shadowing here and there throughout 2 years or so - she was also successful.
If you're worried about yours, list them and we can help from there.
Not so much worried but just looking for some feedback since I had zero activities freshman year except research. Thanks to all for the notes. Here they are (I'm a junior, btw):
est. Oct./Nov. of 2019 tutor/mentor for multiple orgs targeting disadvantaged communities (400+ hours)
est. mid 2019 red cross volunteer; est. mid 2020 blood donor ambassador; est. jan 2021 covid vaccine aid (100+ hours)
ED volunteer est. nov 2019 (80 hours)
Shadowing (30 hours)
Clinical spanish interpreter est. late 2020 (20 hours)
One lab since late 2018; 1 presentation; 1 poster; 1 review pub (cell, 3rd); 1 research pub (nat mater, 4th); 3 funding awards during academic year; 1 formal internship funding award during sophomore summer
It's fine, I had basically 0 activities freshman year as well. You seem to be on good pace with your clinical activities. Keep up the volunteering/interpreting and you'll be fine. Your nonclinical volunteering is great, and your research is exceptional.