CLV is only there because the original 6502 had a SO (Set Overflow) pin, so if you wanted to test that pin, a CLV would be needed to remove the possibility your last ALU op set it.
BIT isn't super useful and is generally used to allow multiple entry points into a subroutine with slightly different starting instructions, not something it was intended for and not really needed.
There's a few instructions that aren't used that often unless you're being really hacky:
- RTI isn't something you'll normally be using unless you're writing an IRQ handler.
- TSX/TXS are only for changing the stack pointer, not a usual thing but might be used at times.
BIT isn't super useful and is generally used to allow multiple entry points into a subroutine with slightly different starting instructions, not something it was intended for and not really needed.
There's a few instructions that aren't used that often unless you're being really hacky:
- RTI isn't something you'll normally be using unless you're writing an IRQ handler.
- TSX/TXS are only for changing the stack pointer, not a usual thing but might be used at times.