The human body is curvy and complicated, and each one is completely unique. As a result, there is some guesswork involved in the fitting process, and the first bra won't be perfect. The band will fit well, the cups will be about the right depth, and the wires (if there are any) should be more comfortable than whatever you're used to, but there may be small imperfections in the fit here and there. Bottom line, if you struggle to find bras that fit, then your made-to-measure bra will be better than anything off the shelf.