Is it permissible to complete ablution if the head dries while washing the feet, or if the right hand dries without the left while wiping the head, or if the limb dries with only a few drops of water remaining on it?

It is advisable to ignore obsessive thoughts (waswasa) and not pay attention to them. Therefore, do not wash a limb more than three times. Wipe the head and ears only once. For the completeness of purification (tahara), a strong presumption is sufficient, so do not pay attention to the whisperings of Satan. Wiping the ears is a Sunnah (definition), and its omission does not affect the validity of the ablution (wudu). Do not worry about an imaginary dryness of a limb. Act according to the opinion of those who do not consider continuous sequence (muwalat) obligatory until the obsessive thoughts disappear. Your purification is valid, Allah willing.