piecemeal
Done in small, separate steps instead of all together.
Piecemeal means doing something bit by bit, in separate pieces rather than all at once in an organized way. When you clean your room piecemeal, you might pick up your books one day, organize your desk another day, and finally vacuum a week later, instead of tackling the whole job in one session.
The word often suggests that this scattered approach isn't the best way to handle something. A school might add piecemeal improvements to its playground: a new swing one year, a slide two years later, fresh paint eventually. But if they had planned everything together from the start, the playground might work better as a whole.
Sometimes piecemeal work is necessary. When you're learning a difficult subject like algebra, you absorb it piecemeal, mastering one concept before moving to the next. But when building something like a treehouse or writing a research paper, a piecemeal approach can create problems: the pieces might not fit together well, or you might lose track of your original plan.
When someone criticizes a piecemeal approach, they usually mean the work would be more effective if done systematically, with all the pieces planned together from the beginning.