In general, I'm less critical of Tilke's tracks than many people are, but there is one trend that I find a little perplexing. All of Hermann's permanent circuits have been nearly the exact same length with a similar amount of turns. There's only about a 1/10th of a mile length difference between all 7 of his permanent tracks that F1 has raced on.
Sepang: 3.44 mi. - 15 Turns - 56 Laps
Bahrain (Pre-2010): 3.36 mi. - 15 Turns - 57 Laps
Shanghai: 3.387 mi. - 16 Turns - 56 Laps
Istanbul: 3.317 mi. - 14 Turns - 58 Laps
Valencia: 3.367 mi. - 25 Turns - 57 Laps
Yas Marina: 3.451 mi. - 21 Turns - 55 Laps
Yeongam: 3.492 mi. - 18 Turns - 55 Laps
Aside from Valencia it's not like open space could have been an issue, as these circuits have been built on sprawling expanses of land/swamp/desert. Has this length been mandated by the FIA as a pre-requisite for Formula One participation?
Whatever the reason for the cookie-cutter length, I believe it is partly responsible for some of the low overtaking totals Tilke tracks can produce. While some of the older, classic F1 tracks were very long (Hockenheim, Osterreichring, Spa, Old Interlagos), several of them were quite short by today's standards.
In the 1982 season, 8 of the permanent circuits used were significantly shorter than Tilke/Bernie's "chosen" distance. If you add Silverstone to the mix, that makes 9 circuits in regular use that come in under the "golden" length of today. Aside from the fact that there was often better overtaking opportunities on these tracks, with the additional laps, there was automatically more overtaking chances.
Kyalami: 2.55 mi. - 77 Laps
Jacarepagua: 3.12 mi. - 63 Laps
Imola: 3.13 mi. - 60 Laps
Zolder: 2.64 mi. - 70 Laps
Gilles Villeneuve: 2.740 mi. - 70 Laps
Zandvoort: 2.64 mi. - 72 Laps
Brands Hatch: 2.61 mi. - 76 Laps
Dijon: 2.36 mi. - 80 Laps
Silverstone: 2.93 mi. - 67 Laps
So not only has modern circuit design helped in reducing overtaking figures, but I think the modern circuit length has played a hand as well. Whether this is forced upon him by the FIA, or an obsessive-compulsive component of Tilke's track design philosophy, I do not know, but the theme appears to have continued in Hermann's plans for the Austin, Texas layout. Coming in at 3.4 miles with 20 turns, it is quite consistent with his previous creations.