This question cannot be answered with a clear YES or NO.
What exactly does reward mean in this context? "Worthwhile" is derived from "reward", the payment for a service rendered. In the same way, one could also ask before a restoration: Is it worthwhile? First of all, a restoration preserves the value of the object and can, under certain circumstances, even lead to an increase in the value of the furniture. It can lead to a measurable and non-measurable increase in value, a qualitative or financial increase in value. Sometimes more importance is attached to the non-measurable value than to the pure market value.
Financial value of a piece of furniture:
The purely financial value of a piece of furniture is based on the market, on supply and demand. Prices go down or up. For the old furniture itself it means nothing. Only the market value has changed. For a current sales value of a piece of furniture, one should inform oneself in the antique and art trade as well as at auction houses or on the Internet.
Qualitative value of a piece of furniture:
Old furniture was made to a high quality, exclusively by hand until the beginning of industrialisation. This gives them a very high qualitative value, otherwise they would not have survived the years. Comparable furniture is reproduced today in very good joiner's workshops. However, the production price is far higher than the purchase price of the old furniture including its restoration costs. The new old furniture is virtually created from scratch.
If you own an old piece of furniture that you love and cherish, it is worthwhile to have it conserved and/or restored, if only because of its good craftsmanship.
Age value of a piece of furniture:
Historical furniture is unique simply because of its history, its material and its workmanship. Very often only individual pieces have survived. An exception is, for example, collections of armchairs or chairs. Over many generations, this furniture has "experienced" and "seen" a lot. Their use has created a patina on the surfaces that no new object can compete with. But should an old piece of furniture be left to decay, deprived of its raison d'être? Every cultural object is a handcrafted original, a contemporary witness to the art of craftsmanship.
The ideal value of a piece of furniture:
or many owners, the ideal value of their furniture is important. A chest of drawers owned by the family cannot be replaced by anything else. Family tradition, family stories and one's own memories are associated with such furniture. Such objects are truly unique, whose signs of age and use "tell" history. It is often the traces of use that make up the charm of historical furniture.
So when the question arises as to whether restoration is worthwhile, one should ask oneself: What does this piece of furniture mean to me personally? Is it worth this financial effort for me?
With real designer furniture by modern designers, important names, the answer is usually easier.