If you are interested in the factors that have led to the court backlog then you can start with the lack of investment and loss of experienced staff.
As for Jenrick suggesting courts sit around the clock - we don’t have the staff or facilities to do this largely because of the lack of investment and (any) strategic planning since 2010!
The Tories were quite happy to cling to the title of party of law and order when it suited them (ie extend prison sentences) just not so much when it came to investing in the systems that kept courts running. Bloody Hypocrites.