The most important fact is having a good clean roof substrate, is keeping any loose debris clear of the membrane before installation.
The advantages of the mechanically fastened systems are that less mechanical attachment of insulation vs. fully adhered roofing systems. A smaller crew is possible, and not quite as a labor intensive as other single plies systems.
Virtually no waste as all the discarded sheet goods can be utilized on the mechanically attached roofing system. The bonding adhesives in the field areas can be eliminated from use. The lightest weight of any installed thermoplastic system, the mechanically fastened system has a reflectivity of white sheet vs. rock or paver ballasted systems. Minimal installation equipment is needed for the attachment of the mechanical systems.
Half sheets are only required with the mechanically attached systems, T-joints are required on all 60 and 80 mil TPO and only 80 mil on the PVC. If the roof you are working on backs up or butts into a higher building, you don’t need half sheets at that particular wall. If installing a fully adhered system, there is no need for the fasteners at a change of plane detail. The fasteners are required for all the mechanically attached and ballasted systems. All the valleys in all Everguard systems must be adhered to the roofing system itself.