I Tend to make two tunes for each car in each class, an outright grip setup and a speed tune for when it is needed.
I use brands hatch as my grip tuning track now as it has a lot of different cambers, uphill and downhill braking and generally a car that behaves there will be a good setup anywhere else. Also I can run the same track in the wet too which always a good indicator as to how good the tune is.
For most classes I just work out for each car what its good at, build that car for that purpose and then tune it.
I will test builds to work out what build works best and then settle on that builkd for that car for its purpose.
Occasioanlly a favorite car or certain cars will be multipurpose where multiple builds will be beneficial.
Normally i tune for a grouping of tracks, ones that are similar, then ones like lemans or ovals require a tune specific for that track. I tend to run the oddball cars that arent leaderboard top 100 and try to get them there so there is a number of alterations and/or builds ill try to achieve(i hope) to get the times up higher.
Btw any tuner/group/team looking for help, or a lap buddy, or someone to bounce your tunes off of im getting bored of tuning and lapping alone lol. Hit me up, shoot a msg, like meeting new ambitious tuners/lappers!