I (also) can't see much sense in using a general multi-vitamin if we don't know what we need.
I tried a specific supplement protocol for fibromyalgia, which didn't work at all for pain, fatigue or anything, and about 100 individual supplements. Of these ~45 work for muscles, sleep and energy. But most (also) are all far from the beaten track, like specific amino acids, which I have to dose fairly high.
The most striking experiences were deficiencies recently that chime in with the other two's recommendations: phosphate (mineral), proteins and riboflavin (vit.B2), all important for energy. The first two were chance findings, and riboflavin was deliberate, wanting to know how all my B-vitamins were behaving.
The normal ones that are often checked, D3 & B12, were low, but didn't make a difference, same magnesium which can't actually be checked properly.
Multi-vitamins often have too few amounts and cheap & ineffective forms of vitamins & minerals.
My new practitioner has recommended two specific combination products for my conditions amongst other things, with many less usual contents, and I already supplement most singly, however much higher (some 10x as much) and in more effective or better forms for me. Some supplements need to be taken before meals, so it wouldn't be effective to have them in with a combination product.
Starting point to build up your own individual collection would be targetting your personal symptoms using more reliable webpages & the recommendations on this forum, flanked by the protocols of fibromyalgia functional docs like Jacob Teitelbaum (SHINE protocol) or Rodger Murphree.