As per 36.133 3gpp specs below is mentioned
126.96.36.199 Measurement and evaluation of serving cell
The UE shall measure the RSRP level of the serving cell and evaluate the cell selection criterion S defined in  for the
serving cell at least every DRX cycle.
The UE shall filter the RSRP measurements of the serving cell using at least 2 measurements. Within the set of
measurements used for the filtering, at least two measurements shall be spaced by, at least DRX cycle/2.
If the UE has evaluated in Nserv consecutive DRX cycles that the serving cell does not fulfil the cell selection criterion S,
the UE shall initiate the measurements of all neighbour cells indicated by the serving cell, regardless of the
measurement rules currently limiting UE measurement activities.
If the UE in RRC_IDLE has not found any new suitable cell based on searches and measurements using the intra-
frequency, inter-frequency and inter-RAT information indicated in the system information for 10 s, the UE shall initiate
cell selection procedures for the selected PLMN as defined in .
So UE performs measures of serving cell during every DRXcycle.