So cant find a solid answer on this....

Going through full workflow and applying deflicker, I know I've very little shift in luminance and am happy to apply nominal deflicker amount, save and hit export in LR. Then move onto my next sequence.
However once saved after deflicker, LRT recreates the previews. When I shift onto next sequence I'm prompted if I want to let LRT continue making previews in background (using plenty of processor resources etc). What are advantage/ disadvantages to this?
If its only previews then, its just for checking surely? I had some hiccups in workflow before and am unsure if this was a contributing factor - just keen to rule it out I suppose.

thanks in advance

If you don't want to deflicker a second pass (refine), after saving I'd recommend turning off the visual preview generation, since usually you wouldn't want to waste processor power on generating the previews again.
So just click on the "Visual Preview" button again, to disable the generation before changing to another folder, or say "no" to the dialog.

The ability to do the preview generation in background comes handy, if you want to start editing another second while the previews for the first are being generated.