Summary: Worklog data is not stored according to the user profile time zone but specific to the server timezone (UTC).

Problem Definition:
This can create confusing results when users from different time zones are entering time. It is hard to gauge without some manual conversion what time they actually. In some cases it can throw the figure off by day i.e. 10/31/2017 5 PM PST Converts to 11/01/2017 2:00 AM CET.

Suggested Solution:
Have an additional field where worklog entries are stored according to the user profile timezone. See comments by Mark on JRA-35503.

Why this is important:
Right now there is unnecessary friction and leg work for the users end to correct this problem.