This depends on the strings: you can handwrite many mathematical expressions more quickly than you can type them in most setups. This is especially true for things with a lot of super/sub scripts. It's *especially* true for symbols not in the character sets available to you.
Also, sometimes the same *content* can be recorded more quickly as handwritten math/logic than as typed strings.
Sometimes handwriting is faster, sometimes typing is faster.
Therefore, the fastest setup is one where you can switch between handwriting and typing seamlessly, such as on a tablet PC on some sort of stand situated like an easel with an external keyboard at elbow height, or at a desktop with a keyboard and graphics tabletin which case, for the monitor position, you don't have to compromise between what's good for your hands/arms and what's good for your eyes/neck/back.