For 100baseT, there is apparently a hard 100 meter limit that is due to collision timing issues, in addition to signal strength issues.
For 10baseT, the 100 meter limit is due to signal strength issues ONLY. Modern cat5e cable has less attenuation than does the cable for which 10baseT was originally speced (which is not even cat3 cable, but just plain old telco grade twisted pair, like what might have been used to wire a Merlin phone phone system in 1985) and therefore it is apparently possible to run 10baseT up to 150 meters on cat5e cable without issue.
