leetcode is a good idea - but coding problems are more like to get foot in the door (pass phone screen). Senior and above candidates are "leveled" and judged using design and behavioral questions - so the way you answer them would impact level and target compensation significantly. So it make sense to spend time preparing for Systems' Design questions Behavioral questions.

From another point of view - design and behavioral questions original goal is to confirm that candidate have related experience from day to day work, so if you have enough practice on your current job - it is not so much time to prepare for design and behavioral part of interviews.