There is a great range of wood preserving products on the market and with due care and attention the lifespan of wooden windows etc. can be greatly extended. The addition of awnings can also help as the window in the last photo is north facing and about 10 years old. You can see it is in great condition still and the maintenance timing is good to let it last another 10 years.
In the second photo these windows were installed in 1972 and have never seen paint – only Cabots stain and varnish and they are as sound as the day they were installed. Just the regular application of product has kept them in great nick.
The vanity shot is using a one coat product. Once the correct stain colour was identified the colour match and finish made my client very happy.