Post shore spacing is never a rule of thumb — it comes from your engineer of record's design based on the slab thickness, the concrete and live loads, and the shore's rated capacity.
Aluminum shoring beams span between the shores to carry the formwork. Tighter beam spacing carries more load; your shoring plan specifies both the shore grid and the beam layout.
On multi-story pours, re-shoring transfers the load of freshly-poured ('green') slabs back down to cured floors below. Florida Building Code §3107 governs how this is done — always follow the engineered re-shore plan.
This guide is general information, not engineering or legal advice. Always follow your engineer of record and local code.