If it's not a short-term collaboration, 'Leader Name and a Band' is still one group, no different than 'Just a Band'. And in some cases, the only person who gets to decide if it's the same band is the bandleader, regardless of whether their name is in front of the band. Billy Corgan can grab four random musicians, and if he says it's the Smashing Pumpkins, we do too. Molly Hatchet's first and tenth albums have no common bandmembers, but they're both still Molly Hatchet albums. For major orchestras, the band members are basically irrelevant.
Jazz ensembles are basically the same, even if they're led by and named after a bandleader. Whoever Dizzy Gillespie put in a room when the tape started or the curtain was drawn was his band. If there were four people on stage, it was the Dizzy Gillespie Quartet. If there were seven, it was the Dizzy Gillespie Septet. When the person counting ran out of fingers, it was the Dizzy Gillespie Big Band; if he ran out of toes it was His Orchestra. Occasionally Gillespie or somebody at the record company would drop in the phrase "All Star" for some reason.
Years later people making compilation albums would use whatever they wanted. Nobody could keep track of how many different releases of the same sessions or concerts were made, let alone what exact phrasing was used at the time. Music DB sites like ours or Discogs want to error on the side of caution, so we just make new profiles and pretend we'll sort it out later.
I'd suggest this for jazz or big band or easy listening bandleader, just using Gillespie as an example: keep a solo profile for Gillespie as a person. File any solo releases under that and use it for any place he's credited as a guest with another ensemble, relationships, composition credits, etc., same as we do now. Then take any artist pages that are "Dizzy Gillespie [band]" and merge them into a single artist, keeping the existing artist credits, or updating them to match what's on each release. Gillespie would still be a member of this band -- probably the only continuous member, so these would still use one artist credit: ["Dizzy Gillespie bands" as "Dizzy Gillespie's All-Star Debacle"], not ["Dizzy Gillespie"]'s ["Dizzy Gillespie bands" as "All-Star Debacle"].
The only exception would be if the bandleader treats a specific lineup and band name as a special group. If the group lasts a long time with the same core members, the bandleader uses a different band name if it's not that group, and/or if it's a specific kind of music that's a departure from his than his other groups, then an argument could be made that that's a distinct artist based on AI.