Monday is the best day for you to buy your bitcoin?

In the graph, we could easily see and conclude that Mondays are the top average return of all days in a week. Also, we could see that Wednesday and Thursday that has average return of -0.09% and -0.23%.
In my opinion, I think for long term investment these days doesn't really matter anymore as long as we do buy low and sell high in the market, but I do believe that this analysis is on point in weekly investment or short term investment.
What are your thoughts about this?