Does link disavow tool do anything?

This is a case study involving dejanmarketing.com domain and impact of link disavow file removal on its vulnerability to ongoing algorithm updates. Our reasoning for this test was that brands "Dejan SEO", "Dejan Marketing" and domain "dejanmarketing.com" had enough recognition and organic link authority that a few weird links couldn't possibly harm its status in search results. We observe over a year worth of Algoroo SERP flux data against the Search Console position data for "SEO".

• 23 May 2017: Deleted link disavow file
• 07 January 2018: Multi-week update. Impact: Negative
• 21 February 2018: Unknown update. Impact: Negative
• 09 March 2018: Multi-Day update. Impact: Positive
• 01 April 2018: Unknown update. Impact: Positive
• 25 April 2018: Unknown update. Impact: Positive
• 24 May 2018: Unknown update. Impact: Penalty-Level Event
• 10 July 2018: Uploaded new link disavow file
• 3 August 2018: Core algorithm update. Impact: Recovery-Level Event

Between disavow file removal and June 2018, no content or layout changes were made. We conducted one content test in the first week of June (with zero impact). It appears that some core algorithm updates at Google changed how they evaluate link signals and in the absence of link disavow file, our rankings were a roller-coaster. The key event was the 24 May update which caused a massive drop. No other convincing reasons were found other than some questionable links in our otherwise organic link profile. At this point I'm inclined to think that link disavow file did its job and provided a convincing partial recovery with the last core algorithm update.