Everyone daydreams, because all types use all eight cognitive functions. Daydreaming about things that may never, or has yet to, occur takes Ni. Daydreaming about the past utilizes Si. You don't daydream with Ti and Fi because they are both action based cognitive functions. Instead, when in deep thought and analyzing a current problem Ti emerges, and when determining whether something fits into your value system you use Fi. All four functions may be misconceived as daydreaming, however only Ni and Si can be used for this type activity.