|Mar Ukva said, "I am vinegar the son of wine", in our language he didn't reach the toenails of his father. Why? Because his father waited 24 hours after eating meat before eating cheese while he only waited until the next meal, no matter how close in time.
Mar Ukva and every Amora were on such a high level that we cannot even fathom. If Mar Ukva was so amazed by his father's greatness in waiting twenty four hours, why did he not just do the same? Surely it wasn't his constant craving for beef!
Rav Avigdor Miller explains that it is not wise to accept on ourselves things that are beyond our true level of Ruchniyus. Of course Mar Ukva could have refrained from meat for a full day just like his father, but he was not holding by that madreiga. It would have been to a degree disingenuous. He lamented that he was not on a high enough level to sincerely take upon himself this Chumra.
Similarly, in the next piece of gemara Shmuel says that his father surveyed his property twice a day, while he himself was only on the level to do so once a day. His father understood the value of every little thing Hashem bestowed on him and watched it like a hawk. Shmuel felt that all he could manage with this same zeal, was once a day. The second time would have either been insincere or worse yet made him think that it is his care that makes his business flourish. His father had no such problem.