Mathematics is not the same as chess, but here is an anecdote from the Preface of Jan Timman's book The Art of Chess Analysis that you may find interesting.

In his Foreword [to One Hundred Selected Games], Botvinnik asks the rhetorical question, "How do I prepare?" and he immediately answers, "That has never been any secret": fifteen to twenty days in the fresh country air, prescribes Dr. Botvinnik.

So it was that Hans Böhm and I, among others, bid farewell to our carefree lifetstyle and began a long retreat at a house in the Friesland countryside. For three months we lived like health fanatics. Our luggage contained little more than chess literature and track suits.

The tournament began…and the first five games were lost. I remember exactly how I felt. During play my body was overflowing with so much energy that I could hardly stay seated in my chair. After each game I still had enough energy to run several times around the Vondel Park. But why bother?

This painful start drove me to a firm decision. I threw all my Spartan habits overboard and indulged myself in everything that had been declared unhealthy. In short, I went back to my old lifestyle. And lo and behold, immediately everything went wonderfully. Thanks to a good winning streak, a total catastrophe was averted and I managed a reasonable result.

So much for that part of the wisdom I had hoped to find in Botvinnik's work. The only lesson I really learned is that you must never change your normal rhythm just because you are faced with an important tournament. As Botvinnik says a little later in the same Foreword: "Possibly some of my suggestions will not be of much benefit to some players; each must consider them critically and apply them with caution, taking his own individual capacities and habits into account."

I should mention, for the benefit of those who do not know anything about Botvinnik, that he did indeed have a lifestyle with daily exercise built in, and he did attribute his success in part to that. So it's not just a matter of Timman misinterpreting the meaning of "fifteen to twenty days in the fresh country air."