nosemineb – some of this may be useful.
For what it’s worth the hourly average speed works out at just under three miles an hour, with the terrain and height gain, (which I can see from your posts you are familiar with,) this is not ‘only walking pace’. I’m sure you realise this.
I supported a mate with a winter attempt last December and having the route GPSed really helped.
Stage 3 seems to be the one most drop out on. At this point just focus on Wasdale not what is left total.
Change your socks at all the road crossings.
Don’t wear new / untested footwear or clothing.
Have road shoes to change into for the run into Keswick.