Come on. We all know that operators, Thameslink especially, bung out minimum formations whenever possible off-peak, regardless of the revenue they are taking in the ticket office, just to minimise the mileage-based element of the leasing payments. Half the fleet or more will be sat in sidings. As for cleaned/maintained - my car goes in for servicing one day a year nowadays - why do Thameslink need 50% of the week to sweep out, bung through the washer on the move, and check the light bulbs?
I'm sure that when the new 8/12-car fleet comes along we'll never see the 12-car units from 1900 Friday to 0700 Monday, miraculously the 12s will need all weekend for cleaning and maintenance while the 8s will be able to run right through.
Complete crap and baseless opinion I strongly disagree with.
We already see 12 cars runnig around from 0518 until 2235, with the future fleet requirements will see the 12 cars in service at weekends as there simply won't be enough 8 cars to use on all Thameslink services. As for 50%, think you'll find is nearer 25% step down for off peak services. And that's mainly achieved by services being extending to the depot, which on Thameslink
currently is a single location for all 319s and 377s. Next month Thameslink gets its second depot meaning there will be more balancing of requirements and not one single small location to do it work (Hornsey becomes the other depot stages leaving Thameslink with two depots).
However I think you'll find that your car does far less miles than any Thameslink trains that's tend to be for around 18 hours a day the longest diagram for a Thameslink service being over 24hrs of constant use.
What you may not realise that for Thameslink, off doesn't actually last long. The Bedford to Brighton services is around 2.5hrs. Therefore complete round trip actually means don't have time between the peaks to destrengthen and the restrengthen services so you them run all day. This is one of the main reasons why Thameslink is getting fixed formation stock as there just isn't the time between the peaks to make the trains short.
As for the 700s at weekends, well the plan/contract is 12 cars at weekends. This is achieved with the requirements for less services like the peak period allowing maintenance to take place.
I believe your post is just a rant that's actually based in reality.