I have several columns with time values. With a Data Validation, I display a list that takes the values from a hidden column with a large range of time values. Depending on the value of another field, I can take portions of the range to display the value list. That works perfectly:

I have several columns with time values. With a Data Validation, I display a list that takes the values from a hidden column with a large range of time values. Depending on the value of another field, I can take portions of the range to display the value list. That works perfectly: