Lead time and reduction of lead time is an important part in Lean Manufacturing. Lead time is the time it takes from when a process starts to it is completed. In manufacturing and software development lead time is important to manage if you need a short time to market.
An examples is, if you place an order for a new car and you will get the car in 6 months, the order lead time is 6 month.
In software development it means the time it takes from identification of a requirements and when it´s in production. In Kanban “for software development” measuring lead time or cycle time is a critical part of the Kanban method so if you need to start track you lead time try Kanban.
Keep your lead time as short as needed from the market and stakeholders point of view.