Importance of Schematic Grids
Schematics should be entirely done on Altium’s 100mil grid with component parameters being the notable exception where 50mil grids is legal. Component Symbols should be designed to comply with this rules and therefore pins must be placed on 100mil grid in the symbols.
An explanation as to why this is the case will be drafted in time. See Schematic Symbol and Footprint Guidelines for some information as well. This specifies normal pins should be 200mils long, but in special cases differ pin lengths are permissible as long as the tip falls on a 100mil grid. So for example if you place a pin on a 100mil grid in the symbol and the pin is 150mil long then it violates the requirement as to use that pin you will then need a 50mil grid in the schem.