You're in the right place
I don't think & and repeat will be compatible - exiting out of execution mode to prompt for a value and keeping in synch with the time interval wouldn't be so much fun
theoretically though, && would make more sense, but I don't see that working.
I can't tell you I"ll log a bug, but I'll dig to see what we intend to support here.
So I've logged a bug for the scenario using && in a repeat - it should reuse the value.
We won't be supporting & in a REPEAT