How does the planning affect the project schedule positively?

Project planning is key for its delivery. In lay man Time is Money, by proper planning we can save time by logical and detailed schedule.  Planning includes project budget by analyzing Man, Material, Machinery etc. We can save time and money by proper planning.

Proper project planning includes a logical and detailed schedule.  The project plan is not complete without a budget and the budget is largely dependent upon the schedule.  Labor is not a fixed cost and can be a significant cost if not managed according to a schedule.  It is through the project planning process that the milestones and key performance indicators are determined and through the schedule and budget that they are measured.  A detailed project schedule is an invaluable tool in a well managed project.

They provide a basis for you to monitor and control project activities

They help you determine how best to allocate resources so you can achieve the project goal.

They help you assess how time delays will impact the project.

You can figure out where excess resources are available to allocate to other projects.

They provide a basis to help you track project progress.

Planning provides the yard-stick for measuring the project progress. A thorough schedule developed during planning stage always provides an insight to what's happening during the execution stage. Planning is one of the most important phase of any project life. The better the planning is, the better is the project delivery.

Planning always provides you the time for specialize  (check-list) the work scope for your team one by one  

and for your budget management. Most important  day today work management will in process which will helps you to improve as an individual and team as well.