Li ions are highly mobile in LLZO even at very low temperatures, which is obviously also a prerequisite for its application as a solid-state electrolyte. Two implications of this mobility is that, firstly, after sintering, all Li Frenkel pairs that emerge at elevated temperatures will relax back to the equilibrium RT concentration upon cooling. Secondly, when LLZO as an electrolyte layer is in electrical contact with a Li reservoir, like e.g. a Li metal anode, the Li concentration in LLZO will adjust according to the concentration of aliovalent dopants in the structure, regardless of possible Li loss during high-temperature synthesis and processing. In contrast with highly mobile Li, cation dopants are expected to be highly immobile due to their higher formal charge, low polarizability and general refractoryness of LLZO as a host crystal. Hence, the concentration of dopants is expected to freeze-in at elevated specific temperatures, causing non-equilibrium defect concentrations at lower temperatures. This situation has been described as broken ergodicity by Grande et al. and the freezing-in of point defect populations is well-known in solid state ionics. In the following we discuss the experimentally important distinction between synthesis methods were the final cation stoichiometry (with the exception of Li) of the sample is constrained to the nominal stoichiometry of the precursor materials, and the situation where the final sample of interest can freely exchange dopants with the surroundings. Examples of the former situation are solid-state and sol-gel synthesis where all reactants contribute to the final sample material, thus maintaining the nominal stoichiometry. The latter situation applies to e.g. thin film deposition methods like pulsed lased deposition (PLD) or sputtering where there is not necessarily stochiometric transfer from target to film, and where there can be substantial segregation to the film edges, which are usually not investigated. Single crystal growth from melt and hydrothermal crystallization are also methods where the nominal composition of the reactants are not necessarily reflected by the true composition of the final material.