Well, I found this 'revealing' enough.
Wait, I thought it was only 4 weeks. Pretty sure I'm correct as well.
If fed were to make the miami finals which is played on 4/1 and then the second round of madrid will be on 5/9. That's 39 days between matches or 41 days if he loses in the semis. 6 *7 = 42 days. So it's approx 6 weeks depending on if he makes it to the semis or finals. THATS ALOT OF TIME especially when your on such a huge roll and nearing a grand slam nearing mid season.
Its comparable to the amount of break fed had at the end of the season after winning world tour finals till the australian open but that was about 50 days a bit longer sure but in that time fed played an abu dhabi exho, played DOHA open, hurt his back,played hurt,withdrew from doha, rested his back, flew to australia, and started the australian open.
And that was at the end of the season break. Long ass time like I keep saying.