Using LWRP, shadow casters are more, this seems to be something to do with the shadow culling of SRP. In builtin pipeline we get less shadow casters with the same settings.

Repo Steps:
1. open attatched project
2. check shadow casters either in the stats or the frame debugger, make note
3. switch to LWRP by asigning the lightweight asset, change the 'New Material' shader to 'Lightweight Render Pipeline/Lit'
4. check the shadow casters in the frame debugger

Expected outcome: The shadow caster count should be the same as they have the same settings
Actual outcome: In LWRP there a number of extra shadow caster drawcalls

Repoed in Unity 2018.3.0b4 & LWRP 4.0.1