It’s faster with a focused guild on LSTB any sized guild can have R3+ clones and get up to 50 shards. Mk3 is limited to stars obtained where lower GP guilds may get as little as 10 shards, as success in stars is linked to GP. Then you could run LSTB and ROTE getting 30+ shards in LSTB and 10+ in ROTE.
The valid concern is now players will mass purchase KAM these KAM focus guilds will move on. Slowing down progress by limiting to just MK3 farming at 15-20 a month that will take a few years FTP or if the LSB does not return for players in the future.