Let's look at what RT is actually saying:
"Islamic State militants have lost “most” of their ammunition, heavy vehicles and equipment in Russian airstrikes, the Defense Ministry said Tuesday. At least 86 ISIS targets were hit during 88 sorties in the last 24 hours."
86 ISIS targets were hit in 88 sorties in 24 hours. Now I never bought into the myth about ISIS sweeping all before them because the fact is they've not actually fought anyone of note (the Khurds apart who seemed to have kicked their arses) but for Russia to have claimed to have destroyed most of ISIS in 24 hours is laughable.
Western experts seem to agree.
Charlie Winter, a senior researcher for the anti-extremism think-tank Quilliam, said reports on the ground of Isis territorial gains “run contrary to Russia’s claims”.“I highly doubt that even the Russians, who will be party to much of Assad intelligence, know where the “majority of ISIS ammunition, heavy vehicles and equipment” is located
Dr Andreas Krieg, an expert on the Middle East from King’s College’s Department of Defence Studies, said the positions Russia had said it was targeting "have been in the hands of moderate rebels for months now" - not Isis. "They also do not have the precision strike capability that Western air forces have," he said. "These claims that Isis has been significantly weakened are either highly exaggerated or wrong."