Prioritize

Have an achievable goal. That will be your priority. Any other sidetracks are promises that can be achieved but should not be detrimental to the main goal's deadline.
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Deadline is a promise to accomplish the said main goal at predetermined time. Many stakeholders would be expecting the main goal to be completed so that the downline processes will not be disrupted.
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Once the main goal is achieved (or unachieved), proper closure should be implemented, e.g. writing of reports and future directions.
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Once a main goal is completed, any discoveries along the process can be noted and pursued in the next project.
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Hence prioritizing helps to ensure goals are achieved systematically and timely. If sidetracks are "really" promising, an alternative would be to delegate duties or collaborate. Whatever decisions should revolve around completing the main goal within deadlines.