所要時間 and 待ち時間: required time and time spent waiting
Compare journey time with a wait at a counter, checking included intervals before adding them to a total.
The time required for an activity
所要時間, read しょようじかん, means the time required for something. 駅から会場までの所要時間は二十分です。 gives twenty minutes from the station to the venue.
Check the stated starting and ending points. 移動の所要時間 concerns travel time, but the notice must clarify whether any waiting time is included.
The interval spent waiting
待ち時間, read まちじかん, means time spent waiting. 窓口での待ち時間は十分でした。 says that the wait at the counter lasted ten minutes.
待ち時間が長かったので、本を読みました。 says that a book was read because the wait was long. The wait is distinct from the actual consultation or journey.
Checking which intervals are included
この所要時間には待ち時間も含まれます。 says that this required time includes waiting. Adding the same wait again would count it twice.
待ち時間を除くと、手続きは五分でした。 says that the procedure took five minutes excluding the wait. 除くと identifies the interval left out of the calculation.
Should you add the wait again in この所要時間には待ち時間も含まれます。?
Show the answer and why
No. The notice explicitly includes waiting time, so that same wait should not be added again.