The Sprint length decides the delivery of incremental within a time-box. Scrum promotes adaptability. Hence, sprint length can directly be adjusted as per the team’s need.

1. How long should the sprint length be?
   The common question is a decisive factor based on various attributes of your environment. It all boils down to how you would like to deliver your incremental. Frequent requirement changes, team capacity, EEF’s (external environmental factors) and OPA (organisational process assets) affecting the deliverable are some pointers to consider while deciding on sprint length.
   
2. Can i change the length of the Sprint?
   NO. Sprint length does not change in middle of the sprint. Imagine you have a sprint goal and the developers have already mind-mapped the goal with its timeline. As a scrum-master you would never dare to disturb the timeline.
   
3. Can i have different sprint lengths for each sprint?
   YES. The kick-off sprint can be of a shorter length. For every two week sprint the team can have the first sprint for 1 week. (Sprint 0). In fact this is a good startup to gear up your team and ready your environment before the team starts off with their actual development.
   
4. 2-week sprint or 4-week sprint?
   As mentioned, Scrum relies on adaptability. Depending on how your environmental variables behave (this includes Project Manager, Product Owner, Dev Team, Client, EEF and OPA). Ask yourself “how often” is often best !! Does the incremental needs heavy functional development (4 weeks) or a smaller incremental (2 weeks) development can suffice. Longer sprint length can deviate the sprint goal for the team hence Scrum Master ensures no deviation from sprint goal and the team is focussed with daily Scrum Stand-up (Inspect and Adapt).

If the product under development needs faster feedback, reduce the sprint length. Frequent feedback ensures quality deliverable.