I consider a chronograph an indispensible adjunct for safe reloading practice. Simply put, if you're getting higher velocities than the manual indicates, you are probably running higher pressures. It's a safe bet that the people creating the data, usually with an expensive custom pressure barrel, will safely get higher velocities at a given pressure than will us end users. There are no free lunches in internal ballistics.
Used in conjunction with standard methodology (primer appearance, reseating pressure, pressure ring expansion, etc.) a $70 investment will help keep you safe. Depending on chamber finish, headspace, brass quality, and such you may find no outward signs of excess pressure save unrealistic velocities. I have had this happen numerous times.
A chronograph is especially important if you're using non-canister grade powders.
Sam