According to this research paper by Gareth Irwin, Michelle Manning and David G. Kerwin in Wales:
Biomechanics in Sport – KINEMATICS AND ANGULAR MOMENTUM CONTRIBUTIONS TO THE TOE-ON TKACHEV ON UNEVEN BARS IN FEMALE GYMNASTICS
CONCLUSION: The Toe-on Tkachev on Uneven bars … enables gymnasts to increase key release variables, particularly vertical velocity, (and hence flight time) and angular momentum. …
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It appears that even skills like layout Tkachev might even be easier from sole circle than from giant.
Gymnastics Coaching.com 