A genuine work conflict is a reasonable reason to request another interview slot, especially if you ask early and give the recruiter flexibility. It does not automatically signal weak interest.

The problem is repeated rescheduling or a request made at the last minute without a serious reason. One professional change is different from treating the interview as optional.

Keep the message short: explain that a critical work commitment conflicts with the slot, reaffirm your interest, and offer several alternatives.

If you can reasonably protect the original time without creating a real problem at work, that is simplest. If not, request the change promptly rather than waiting until the day before. Use one concrete example to make the point easier to believe and easier to remember.

One reschedule for a real work deadline should be manageable.