Question

Process tailoring is best undertaken on agile projects when

Answer 1

It's best to use process tailoring when they are facing difficulties with the current agile projects strategy or they want to create improvement by trying new things.
Through process tailoring, management could adjust current strategy with unique problems/situation that faced by the organization in order to increase the efficiency.

Answer 2

Process tailoring is best undertaken on agile projects when experienced practitioners want to address an issue, collective wisdom from many experienced practitioners is a get help before attempting to change.  Process tailoring can effective and productive but one should be aware of the risks involved in this practice.