yea, I usually check them with multimeter (20V setting on dial) while cranking. old batteries voltage will plummet down to nothing (like 2 volts) if battery is weak and a helper tries cranking.
It's a good idea to replace batteries after 4-5 years. best if you keep the original receipt and use pro-rated warranty (now usually 7-8 years) towards the purchase of a new one from same chain of stores like Autozone or Advance Auto
generally dirty terminals may prohibit battery charging (even if alternator works fine) and the battery will end up at some point with voltage (at shut off car) below 11V, e.g. after shot distance driving with stereo and lights on... had this happened to wife's car with 4.5 yrs old Duralast battery, just brought it in and got a new (took stronger model with more cold cranking amps instead) one at significant discount ($34 off retail).