From this question on Notion Answers: https://notionanswers.com/2113/convert-property-minutes-split-values-before-after-character

Each Project may have many Tasks required to complete it.

This is a 1-to-Many relationship.

Projects

Each Task may require several “working sessions” (Time Spent entries) to complete it.

This is also a 1-to-Many relationship.

Each of the Task below is named to make the example clear.

“Task1 P1” = Task #1 for Project #1

Tasks

Then, every time you work on a specific Task, you log time for that Task, and relate it to that Task. A Rollup then “sums” the Total Minutes it took to complete that Task in the Tasks table above.

THIS is how you track time correctly in a database.

Time Spent