So I spent the weekend rerolling x-class and sentinel upgrades more than 125 times across 14 different mods for exosuit, ships and multitools. My results are in the pictures. Bolded number sets are upgrades I find desirable, which isn't every single top tier stat roll because upgrades for some mods have potential to boost more different stats than one single upgrade will affect (like jetpacks; 6 different possible stats, only 4 actually get boosted, at most). Notice how the same iteration will give top tier stats for most different upgrades. That means t8yhat the most effective way to get top tier upgrades is to install 50 or 60 upgrades, find which iterations roll these top-class numbers, then restart, burn c-class upgrades until you reach that iteration, save, then try all your different upgrades to see which gives you the stats you like best. Once you choose, you can move on to the next iteration you've found and try them all again.

(Obviously the real reason I'm posting though, is just fishing for accolades on my 120×30 cell, handwritten spreadsheeting skillzsss…)