@MAINJAFAD: Usually, the Luftwaffe aircraft which are to have a special paint job are examples with relatively few flight hours left before some large, periodic inspection or, in some cases, their withdrawal from use. For those few months before their re-painting or withdrawal though, they are used in regular training missions.
For instance, the recently painted "Tiger" Eurofighter will be used as an instructional airframe at Kaufbeuren for the next few years.