Mixing quick response sprinklers with standard response sprinklers can potentially lead to problems (or additional expense) for your comapny. It is definitely a design flaw at the very least.
From NFPA 13 (2002 Edition):
8.3.3 Thermal Sensitivity.
8.3.3.1* Sprinklers in light hazard occupancies shall be one of the following:
(1) Quick-response type as defined in 3.6.2.9
(2) Residential sprinklers in accordance with the requirements of 8.4.5
(3) Standard response sprinklers used for modifications or additions to existing light hazard systems equipped with standard response sprinklers.
(4) Standard response sprinklers used where individual standard response sprinklers are replaced in existing light hazard systems.
8.3.3.2 Where quick-response sprinklers are installed, all sprinklers within a compartment shall be of the quick-response type.
8.3.3.3 Where circumstances require the use of other than ordinary temperature–rated sprinklers, standard response sprinklers shall be permitted to be used.
8.3.3.4 When existing light hazard systems are converted to use quick-response or residential sprinklers, all sprinklers in a compartmented space shall be changed.
From NFPA 13 (2010 Edition):
8.3.3 Thermal Sensitivity.
8.3.3.1* Sprinklers in light hazard occupancies shall be one of the following:
(1) Quick-response type as defined in 3.6.4.7
(2) Residential sprinklers in accordance with the requirements of 8.4.5
(3) Standard-response sprinklers used for modifications or additions to existing light hazard systems equipped with
standard-response sprinklers.
(4) Standard-response sprinklers used where individual
standard-response sprinklers are replaced in existing light
hazard systems.
8.3.3.2 Where quick-response sprinklers are installed, all
sprinklers within a compartment shall be quick-response unless otherwise permitted in 8.3.3.3.
8.3.3.3 Where there are no listed quick-response sprinklers in the temperature range required, standard-response sprinklers shall be permitted to be used.
8.3.3.4 When existing light hazard systems are converted to
use quick-response or residential sprinklers, all sprinklers in a compartmented space shall be changed.