Here is my table before I have made any changes
User        Start        End           Hour
UserA       01/01/2018   05/01/2018    32
Create a custom column to calculate the number of dates between [Start] and [End]
Dates = { Number.From([Start]..Number.From([End]) }
Create another custom column to calculate the number of [Hour]s divided by the number of list items. Do not expand the list before this step!
CountPerDay = [Hour] / List.Count([Dates])
Finally expand your list column to show the number of hours required per day. Note how the dates are in a numeric format. Changing the column data type to "Date" or "DateTime" will change these back to the correct value.
Using my example you should now have a table that looks something like the below:
User       Start         End          Hour     Dates         CountPerDay
UserA      01/01/2018    05/01/2018   32       01/01/2018    6.4
UserA      01/01/2018    05/01/2018   32       02/01/2018    6.4
UserA      01/01/2018    05/01/2018   32       03/01/2018    6.4
UserA      01/01/2018    05/01/2018   32       04/01/2018    6.4
UserA      01/01/2018    05/01/2018   32       05/01/2018    6.4     
If I add the UserB into the mix with the following records:
User        Start        End           Hour
UserB       01/02/2018   02/02/2018    10
The table updates as follows:
User       Start         End          Hour     Dates         CountPerDay
UserA      01/01/2018    05/01/2018   32       01/01/2018    6.4
UserA      01/01/2018    05/01/2018   32       02/01/2018    6.4
UserA      01/01/2018    05/01/2018   32       03/01/2018    6.4
UserA      01/01/2018    05/01/2018   32       04/01/2018    6.4
UserA      01/01/2018    05/01/2018   32       05/01/2018    6.4
UserB      01/02/2018    02/02/2018   10       01/02/2018    5
UserB      01/02/2018    02/02/2018   10       02/02/2018    5