I think shooting jpg for you is a much better option than RAW and
LR.
I would tend to agree ... there are very legitimate reasons for shooting RAW ... but ... if you are shooting high volume, under fixed and controlled lighting conditions ... and ... your client is expecting to receive jpeg files immediately following the shoot ... there really is little reason to waste all the time, energy and space for RAW. Especially when you are using cameras that can create a 36MP image ... Heck I've know wedding shooters that pounded out millions of jpegs from 6-8MP cameras that would rival most folks shooting RAW.
For myself, I shoot RAW on almost every job, except when I have the criteria mentioned above (high volume, controlled shoot, immediate delivery) then I shoot jpeg ...
If you are getting it right before you trip the shutter, and the client is expecting jpeg anyway ... there is little need to go to all the trouble.
I also agree with John ... sending multiple smaller, simultaneous batches to export will speed things up. Unfortunately, in Lightroom, export is not multi-threaded so as to allow users to continue work on another project while the first project is exporting.
Too bad they don't allow for a preference setting to devote all resources to a large export when needed.
Another idea is not to wait until the very end of the day to export the entire job, export smaller batches as you go along ...