There is a GBC resolution on this topic
MINUTES OF THE ANNUAL GENERAL MEETING
SRI MAYAPUR DHAM, FEBRUARY 19 – MARCH 2, 2014
315: Chanting of the Holy Names of Srimati Radharani
Whereas many devotees have expressed concern that the standard upheld during Srila Prabhupada’s presence in regards to the chanting of Srimati Radharani’s holy names and related mantras appears to be diminishing;
Whereas there have been conflicts amongst our devotees arising as a result of not having a definitive policy on this topic.
Whereas although it is neither mandatory nor necessary to do so because all personalities are automatically glorified within the maha-mantra, it is understandable that some devotees may want to emphasize the name of Srimati Radharani on Radhastami;
Whereas it is well known that no one could come before Srila Prabhupada and chant “Radhe Radhe” repetitively as he would not allow it. He always told us to chant the Hare Krishna mantra. Srila Prabhupada himself was never heard chanting “Radhe Radhe”. There is no evidence to show that Srila Prabhupada chanted or encouraged others to chant Srimati Radharani’s names in isolation at any time, including Radhastami. Whenever Srila Prabhupada was greeted with “Jaya Radhe” he always replied by saying “Hare Krishna”, even in Vrndavana.
Whereas there is risk of deviation if we do not follow Srila Prabhupada and the acaryas. Srila Prabhupada disapproved of the introduction of mantras which were not given by the previous acaryas or were not found in shastra
The following should be avoided in all temple and public programs, as well as in recorded media:
(1) Chanting of the holy name of Srimati Radharani without the holy name of Sri Krishna, i.e. Radhe, Radhe, Radhe, Radhe, Radhe. . . .
(2) Chanting of the holy name of Srimati Radharani within mantras that were not introduced by Srila Prabhupada, previous Gaudiya Vaisnava Acaryas, or in sastra, including but not limited to:
(a) Jaya Radhe, Jaya Radhe. Jaya Radhe Jaya Radhe
(b) Radhe Radhe, Radhe Radhe
(c) Jaya Radhe Jaya Radhe Radhe, Jaya Radhe Jaya Sri Radhe
(d) Radhe Radhe Radhe Radhe Radhe Govinda
(e) Radharani ki jai, Maharani ki jai
(f) Radhe Shyam, Radhe Shyam, Shyam Shyam, Radhe Radhe
On Radhastami, devotees may chant Srimati Radharani’s holy name in isolation of Sri Krishna’s name to a limited degree, not more than two or three minutes.
If ISKCON devotees want to give some special emphasis or attention to the glorification of Srimati Radharani, beyond chanting of the maha-mantra, they should do so by chanting mantras or bhajans which are authorized by Srila Prabhupada and our disciplic line. An example of this is the chanting of Sri Radhika-stava from the Stava-mala of Srila Rupa Goswami.
Source – http://gbc.iskcon.org/gbc_res/GBCRES14.html