MONITORING PLACES OF DETENTION : A PRACTICAL GUIDE FOR NGOS 43 ➤ Are there different categories of persons deprived of their liberty under different detention regimes held in the same place? This can mean that more time is needed to examine the different conditions of detention; ■ the work needed to compile the data, which must be done as quickly as possible at the end of the visit; ■ the travelling time between different places of detention, in the case of a continuous programme. 1.3. Frequency of the visits The frequency of the visits can be determined according to: ■ the type of place of detention; ■ Pre-trial detention facilities such as police stations should generally be visited more frequently than penal establishments, as interrogations are held here; ➤ Detainees’ contacts with the outside world are limited; ➤ There is a rapid turnover of detainees; ■ the risks—known or presumed—to which persons deprived of their liberty are exposed, or any protection-related problems noted; ■ the balance to be struck, over time, between the needs of the NGO and the needs of the officials in charge in order to carry out their work. Frequently repeated routine visits can, in the long run, be counterproductive if they disrupt the work of the staff without valid reason.