How to make a time period a variable for this model? (automating the model)

I am trying to make the "Dwell Time(minutes)" in the "Home" sheet into a variable where future users can enter in their desired minutes and it will affect the whole model. The Increments can only be in 15 mins for example in the previous excel sheet we have 90 minutes Dwell time. So is there any way for the user to enter in different increments of 15 mins for that time period?

Ignore the user walkthrough thats for the user to use when using this model. Also, I am returning total days of 60 in cell c11 in "home" sheet when it should be 61, is there a formula that can help with this or should we just put "+1" to make it always return one number higher?


Can you guys please think of some ideas or how I can approach this?

Thanks.