To me this looks like two of the same healer or tank job is still possible, which to my understanding would slow down the LB generation.

Party Composition
When queueing solo or with less than a full party, the Raid finder will match together 2 tanks, 2 healers, 1 ranged physical DPS, 1 ranged magical DPS, 1 melee DPS, and 1 other DPS.The fourth, unspecified DPS class or job to be matched will depend on the settings selected when registering for a raid.

When selecting Duty Completion
The unspecified DPS player cannot be the same class or job as other players to be matched together in a party.

When selecting Practice
The unspecified DPS player can be the same class or job as other players to be matched together in a party.
https://na.finalfantasyxiv.com/lodes...43b40551d1e3e8