Total Floor Fix is make sense to do in older houses with strip floors which are usually squeaky and too old to repair. 

• First: old flooring strips/planks go to garbage
• Second: all old nails need to be removed 
• Third and important!: old subfloor to screw down to joists. This procedure eliminates at least 90% of squeaks 
• 3/4'' plywood to screw down. This eliminates the rest of troules
• new floor to install (hardwood, laminate etc)