Completely agree with FutureLawyer on this!
For each firm: I would recommend asking Grad Rec if they have any preferences in terms of: 1) prose / bullet-points, and 2) whether you should link skills gained back to the role of a trainee.
Should I identify skills + link to TC? Some firms prefer you explicitly name skills gained, other Grad Rec I have spoken to say this is not needed and that they can pull this out themselves. If unsure, I don't think there is any harm in including them, especially if the TC has a particular structure (e.g. if it is non-rotational, I would explain how being proactive, self-motivated, etc. would be especially helpful in this context. If it has an AI seat and I have experience in tech, I would explain how that links, etc.)
Number and range of experiences: I also agree with max 10 experiences, though some app forms might limit you to 6. As FutureLawyer said, I wouldn't self-screen too much, because an experience you might think is not that relevant might turn out to be exactly what Grad Rec are looking for, but I would avoid repetition. E.g., If you have 5 entries focused on collaboration, maybe change one to highlight your written communication skills, ability to respond to constructive feedback, manage time, etc. Similarly, if all your positions are the same (all entries are related to tutoring or even formal legal internships), I would try to add some variety so you have more talking points at interview and so that you are able to show you are a well-rounded candidate. E.g. Retail, volunteering, some legal internships (if you have them), some non-legal internships (if you have them), other part-time or full-time jobs.
Volunteering as wex? I completely understand the comment on no volunteering, but I did actually include volunteering under the wex section in all of my applications! There might be some Grad Rec who don't prefer this, but the people I spoke to recommended I do, and it never came back to me in a negative way. This might have also been because my volunteer positions were quite formal (working at legal clinics, assistant teacher at a primary school, etc.) However, I would add any society positions as extracurriculars.
Content? There are different ways to go about this.
I liked to spend 1-2 sentences describing what the role was (volunteer, part-time worker, manager, team leader, etc.), where it was (a local cafe, a primary school, a multi-national NGO, a boutique law firm, etc.), how I got it (selected as 1 of 20 from 100 applicants after submitting a CV and cover letter, etc.), and the general role (how many hours worked? every week? day? with how many team members? etc.)
I found that my entries would become too long if I literally spoke about everything I did, so I made a table with 2 columns: 'Skills' + 'Experiences'. I would ask Grad Rec or check the firm website to see which skills each firm looks for. If in doubt, you can also look at SRA guidance to see which competencies are sought in solicitors generally. They usual ones would be: collaboration, leadership, attention to detail, communication, integrity, growth mindset, analytical thinking, flexibility, proactivity, time management, problem solving, etc. For each skill, I would find an experience to link it to, then choose which responsibilities and actions I want to speak about accordingly.
For example, if I was speaking about working at a cafe:
- For problem solving, I could talk about dealing with negative customers: A customer was unhappy about a certain order not being available, I made sure to acknowledge his frustration and apologise, treating the situation with empathy and patience, then proposed alternative dishes he might like and offered him the chance to taste test them.
- For growth mindset, I could talk about how I struggled with coordination: Being transparent about my weaknesses, asking other waiters for tips, when a big order needed to be delivered, flagging this to colleagues beforehand and finding someone who would be able to help me bring dishes to the table later.
These are just some examples! It is great if you can also give an outcome / quantity! If you were a tutor, how many students did you work with? Of what ages? Did they see an improvement in grades? Etc.
I hope that is helpful and all the best with your app!!
I also relate to this sensation, don't worry, you're not the only one! After a bad test, I like to treat myself (go get some rest, night out, have a snack)! I also like to treat myself after a good test... I guess I just like to treat myself generally 
don't beat yourself up over it!
