A wall with an angled section, a nearby column, or a shape that does not match a standard rectangle is one of the clearest signals that an off-the-shelf board will leave a visible gap or simply not fit properly, pushing the project toward a custom solution. In these situations, even a seemingly small adjustment to a standard size can end up costing more in modification than simply specifying a custom board from the outset. Measuring the wall carefully at the earliest planning stage, rather than assuming a standard size will simply work, avoids this kind of late discovery. This applies equally to ceiling height variations, which can affect how a board is mounted even when the wall itself is straightforward.