In what conditions might you consider increasing the volume and/or frequency of quality control checks? What time might you decrease their volume or frequency?

A team member is inexperienced, or just unidentified, the project manager there may increase the volume and/or frequency of quality control ensures till they are satisfied about the work is of an adequate standard.  Same as it is, checks may be increased where difficulties have been uncovered along with a particular individual or region of work.

Where the existing model of checks is uncovering little or no problems, checks may be reduced in frequency or volume and particular team members may be specified more freedom to work into their own way.