Maximally means as much as possible, or to the greatest degree something can reach. If a plan is maximally simple, it has been made as simple as it can be; if a dose is maximally effective, it works as well as that treatment can work. The word is the adverb twin of maximal: maximal describes a thing, maximally describes how something is done or how far it goes. Though actually, everyday English often skips it. People say as much as possible, as far as you can, or to the max. Maximally turns up more in science, medicine, and careful writing, where someone wants a neat, exact ‘to the highest point’ without sounding slangy. It does not mean ‘very’; it means ‘up to the ceiling of what is possible.’