When is it not a good idea to lure out clan castle troops?
Luring clan castle troops out is generally a good idea, as they can sometimes wreck havoc on your troops, however it is not always necessary. For example, if you know what troops are in the clan castle (if someone already attacked the base during war) and they won't disrupt your troops, you can sometimes safely ignore them. To illustrate, if they have all Valkyries or other troops that cannot attack air troops and you are attacking with all air troops, it isn't worth taking the time to kill the troops that won't be able to attack yours.
Some troop compositions are also better at dealing with clan troops without taking significant damage. For example a GoValWi (golems, valkyries, wizards) attack will generally be able to deal with any ground based clan troops, as the valkyries will kill the clan troops quickly with their high aoe damage.
You can also do modified queen walks in which you use a queen and some healers to clear out a portion of the base and pull the clan troops, as a high level queen and a few max healers can deal with pretty much any clan troops, especially if you have a rage spell for them.
Under th8 it is good idea to lure troops out. But later th luring troops is difficult where can be easily triggered by hogs but just seem to as a waste of precious time. So at this time most war bases are large and you will blame why you've wasted your time luring troops out, where you can just kill them on the go between attack. So it's just about personal preference whether to lure or not.