This arXiv preprint (v1, May 2026) by Priya Ghosh and colleagues offers a broad literature synthesis rather than new experimental data, tracing quantum metrology from the quantum Fisher information matrix through frequentist and Bayesian estimation frameworks to multiparameter scenarios under unitary, noisy, and indefinite-causal-order channels. The authors emphasize quantum error correction and reservoir engineering as strategies that extend coherence times, yet mainstream coverage rarely connects these techniques to fault-tolerant quantum networks now emerging in trapped-ion and superconducting platforms. The review covers applications from atomic ensembles and continuous-variable systems to quantum illumination and many-body sensors, but underplays integration barriers such as cryogenic requirements and calibration drift that have delayed commercial atomic-clock miniaturization. Two overlooked threads deserve emphasis: first, the 2011 Giovannetti-Lloyd-Maccone framework in Nature Photonics already predicted Heisenberg-limited scaling in lossy channels, a limit the new review confirms experimentally in atom interferometry yet does not quantify against current LIGO upgrades; second, recent NV-center work in diamond (e.g., 2023 Physical Review X on wide-field magnetometry) demonstrates room-temperature operation at micrometer scales, a practical bridge the preprint mentions only in passing. Limitations include reliance on theoretical proposals without systematic benchmarking against classical sensors at identical size, weight, and power, and absence of economic analyses for scaling beyond research facilities. The work remains a preprint and has not undergone peer review.