Hi and welcome. I am sorry that you lost your dad, is your mom still there on the place? Is she able to look them over, go out in the truck or tractor and check them? My son and I run a cow/calf operation and both of us will check on cattle at different pastures.
@greybeard has given you pretty much standard advise. During calving season we try to make sure we see everyone everyday until the calf is on the ground. When did the cows calve or are they going to calve in say the spring? That will be the more intense time. At this time, if they either don't have a calf on them, or have some good sized calves that should be getting sold, then every 2-3 days is plenty. Again, as
@greybeard said, make sure they have hay in front of them. Also, salt and mineral free choice. Since what you say is that the operation is pretty much well in place, I would imagine that most of the necessary feeders etc are there.
I agree with the chain w/lock on the gates. No need to tempt someone to let them out because they are hunting, or just to be onery. Also, you may want to restrict the field they are in during hunting season and not allow any hunting in their field. Not surprising, some people can't seem to tell the difference between a cow and a deer in the fading light of dusk.....
You can get a spotlight that plugs into your cig lighter or even a hand held one that you can recharge. They are lifesavers if an animal has a problem too.
Is there a neighbor that perhaps your dad was friendly with whom you could get to check them during the week, at least in the shorter daylight times? Maybe someone who he got to help him on occasion? There are possibilities you could explore. And if there is someone who gave him a hand, maybe they are a cattle person and can give you some pointers that you were " too young and lazy" to learn as you said.
Also, is your wife an animal person? She could even go out there mid week, and at least count heads, see if there looks to be any problems. She can stay in the truck and not have to take a chance getting out with your 2 yr old. That might save you a trip in the dark.
Believe me, for 10 years I did all my own cattle until my son finished school and moved down with me as he had stayed with his father 500 miles away. Not by choice but court order. He was down for holidays, and the summers, and learned pretty quick what needed to be done. Did some stupid stuff like all kids, but also learned that I could do it most all by myself and that he was a help if he wanted to be. Needless to say, we have been running our operation now for 25 plus years together full time. We also both have full time jobs, although I am retiring out of mine slowly.
Hope you stick around and hope we can help you out.