Thats exactly how ive seen the way it will be implemented.

Glad I haven't imagined it!!

So for clarity to utilise all 5 subs, you can either...

Make 1 quintuple substitution.

Make 1 quadruple and 1 single substitution.

Make 1 triple and 2 single substitutions.

Make 1 triple and 1 double substitution.

OR make 2 double and 1 single substitution.