Does full Volume encryption put an SSD into a fully used state?
SSDs, particularly of the common MLC variety, have a limited number of writes before the memory cells wear out. Through the use of wear leveling algorithms this is effectively worked around so that the drive has a useful lifespan. The other side of the wear leveling is that it improves performance by writing to unused blocks rather than the much slower operation of reading, erasing, writing to an existing used block. But these algorithms rely on their being unused blocks available.