1/4 second is-- .25
1 second is---- 1.0
If you were looking for a 1/4 second and got .25 you would be right on. If you get less then it is slow at that speed and if you get a higher number then it is fast. How much? You will have to do the math for 1/3 or 1/2 stop differences.
Warm up the shutter a few times then do a run of three and average. It's mechanical and not as precise as you might think, so average.
Worse is when it's warm or cold, it slows down and speeds up depending on the weather. Then there is the position of the shutter, was it pointed down or up or on the side, any of these might change the friction and the mechanics.
Good luck,
Curt