12 Houses of natal chart represents our life and also life of others who are connected with us, what we get in life, even what we loose all are indicated by the 12 houses. As the empty house doesn’t means that, we will not get anything.
Let’s understand with the example; if you’re a landlord of any house which is in city other than your your residence, you goes there once in month to check the conditions of your house, do whatever is required for the maintenance of the house, similarly a planet which is a lord of any house return back during the transit and it could be once in a month or once in a year according to the movement of the planet, Saturn may takes time to return back to his own house.
Conditions remains same for the planets and for you, however you’re living away from the house you takes care of your property or house in any manner, it could be from your ends or by someone of your relatives or by friends.
In a same manner the supportive and friendly planets takes care of the related planet’s house because they are friends in each other, when the transit of planets occurs to the friendly house then it increases the significance of the house.
Some other factors for 10th house
if the lord of the 10th house is sitting in another house or 10th house is empty then, it doesn’t means that, 10th house is devoid from any benefic effects, however the lord is sitting in another house but it takes care of his from various manner, which are stated above.
But if lord of the 10th or any house makes the combination with the 6 8 12 houses lord or occupies the position in these houses then the lord gets weakened and it harms the significance of the house and lord also. Thus there are many other factors also needs to be considered during the strength evaluation of any house or lord.
One more example which would clear your doubts
Example: lord of 10th house is Sun and it is posited in 3rd house, and 10th house is empty but the friendly planet of Sun i.e. Mercury is posited in the 4th house, since both are fiends in each other and Mercury is taking care of 10th house by directly aspecting to the 10th house. On the other hand both are fast moving planets and takes around one moth to cross one sign, thus during transit both of these planets takes care of the 10th house.
I hope this answers your concern.