DD did 2 seasons at L6. We rarely saw layouts, usually RO-BHS-BT. Front tumbling was either FT alone, FHS-FT or FHS-FP. I don't think I ever saw a FT-FT and our group was one of the few that did FHS-FP
I'm just a parent so I don't know what's actually "allowed" or "required", that's just what I saw
The skill on L6 tumbling is pretty high; anything under a C-value is permitted. In concrete terms, this means that going backwards she can do anything up to a 1/1, and forwards she can do anything up to FLO 1/2. Connections don't increase the value of a skill, so any allowable skills can be done in connection.
So for example, if a gymnast really wanted to push the difficulty limits, she could do FLO 1/2-whip-BLO 1/1 for one pass and FLO-FLO for a second pass, and she'd still be fine for L6.
They coaches won't let the girls do whips at her gym but she will ask about working front layouts and will keep working the back layouts. Thanks everyone