Water - Mixable Oils ....?

Just the other day someone who paints beautiful paintings in Watercolour  asked me about Water-mixable oils...

She had just begun experimenting with them, but found they were taking ages to dry enough to move on to the next stage of painting...

I am finding a similar problem with ordinary oils just now.

 I underpaint using thin glazes of oil paint mixed with a drying medium which usually allows them to dry overnight... but its been taking three or four days to dry enough to continue painting.

Dawn Mist, R Colne ( oil on canvas:)

Is it because of the very damp cold weather... particularly perhaps the fog and humidity in the atmosphere ?  Is anyone else finding a similar problem ?   What can we do ?

Morning Mist  (oil on canvas)

Since I have never thought of trying water-mixable oils, I decided to see if there is any advice out there... and came across this helpful website :

https://www.jacksonsart.com/blog/2013/05/09/water-mixable-oils-compared/

"Blue Monday" ?

Is this just another ploy by sales media ...?
like this link I received today, for a blue monday sale by the Society for All Artists:
http://www.saa.co.uk/blue-monday-saa-masking-fluid-bundle.html?utm_source=SAA+Database&utm_campaign=25b7ae5601-EN160117_Blue_Monday&utm_medium=email&utm_term=0_69c0b1655a-25b7ae5601-175364785&mc_cid=25b7ae5601&mc_eid=902c736fec

it does rather seem like it !

One Blue Monday advert suggested cheering up the Monday blues....

well, certainly Mondays feel blue for me as its the day we do our cleaning...and I was never a fan of cleaning !... so if you need cheering up,...

Blue Morpho: oil on canvas by Janet Driver
This beautiful large butterfly landed on this Banana leaf just in front of me
while I was quietly sketching
almost as though asking me to sketch it too...
It stayed absolutely motionless for ages, and then finally, as a reward for my efforts, it began to flutter its wings slightly, gently opening them just enough for me to catch this glimpse of brilliant blue.... only for a few moments... before shutting them again .
It took several weeks trying to paint the brilliance of that small glimpse of blue... it was really exciting to discover how to make that jewel of colour really glow, and I will always remember the stillness and poise of that butterfly.

Blue Dream: oil on canvas by Janet Driver
Another surprising encounter... this time with a tree...
and the same stillness and poise
as  our neighbour's Magnolia tree basked in early spring sunshine