Modern methods in Structural Biology aim to provide detailed insights into how proteins are able to catalyse and control chemical reactions. This requires understanding the role of the conformational dynamics of proteins in the regulation of enzyme catalysis, for example by allosteric phenomena. In recent years, time-resolved (TR) X-ray crystallography and structural enzymology have been revived by the advent of serial crystallography at advanced X-ray sources and by new methods for sample delivery, reaction initiation and data processing, making TR studies increasingly accessible. However, electron density maps resulting from TR studies typically correspond to mixtures of states: their interpretation thus presents a serious challenge, that we are addressing by supplementing TR structural data with ultra-high resolution data from macrocrystals of highly homogenous mechanistically trapped states. Routinely achieving ultra-high resolution requires optimised sample quality, top-hat beams of adjustable size and shape, high-energy data collection with CdTe detectors, and optimised data collection work- flows. In this talk we will present some of our recent work, highlighting what is now possible for Structural Enzymology using X-ray crystallography, yet currently inaccessible by cryo-EM and Artificial Intelligence methods.