Hopefully, you are talking about Critical Path Method scheduling.
Activities (including delivery of material, securing permits and inspections etc) are listed, assigned a time duration, and place in the sequence at the exact point they must occur, to complete a project on the required date.
One analogy I have often seen is a comparison for preparing a Thanksgiving meal. List all the steps, determine in what order they need to occur, how much time each step will take and when dinner is served (or starting with the mealtime, determine when to start preparations to make that time work).
Updating the schedule is a very necessary step.
There are different types of scheduling programs. Constructing a big project without a good schedule is like traveling with no regard to a map or GPI. You will eventually find where you wanted to go, with about the same accuracy as a blind squirrel eventually finding a nut.
Activities (including delivery of material, securing permits and inspections etc) are listed, assigned a time duration, and place in the sequence at the exact point they must occur, to complete a project on the required date.
One analogy I have often seen is a comparison for preparing a Thanksgiving meal. List all the steps, determine in what order they need to occur, how much time each step will take and when dinner is served (or starting with the mealtime, determine when to start preparations to make that time work).
Updating the schedule is a very necessary step.
There are different types of scheduling programs. Constructing a big project without a good schedule is like traveling with no regard to a map or GPI. You will eventually find where you wanted to go, with about the same accuracy as a blind squirrel eventually finding a nut.