So what do you do if you want to know what is on 8 days from now? I used to do it all the time with cable, and I found it very handy.
When I had cable, I only ever scanned ahead that many days if I was looking for a show I had heard about and wanted to see when it was on so I could set a recording. Now I find those shows via the search function. I only ever browse channels or recommendations if I'm looking for something to watch right this minute or say in the next hour (though usually I just pull up something in my library if there isn't a live sports event I have interest in). I really have no need to see what's on in 8 days. Even with sports, I have standing timers for all my teams or special sporting events like the Australian Open, so I don't have any need to scan the guide for the next game date/time. I just click on the team or event's tile to get all the scheduled airings on any channel.
As far as discovering new shows, I have other online resources I follow to learn about upcoming programming, which works much better for me than blindly scrolling days and days worth of hundreds of channels.
And how can you use the search function and record a movie past the end of the guide if you don't know the names of the movies playing in the future? For example, with cable I would often scroll forward in time to see if a premium channel had an upcoming movie that looked interesting in the future. A movie I had never heard of before (and did not know the name of), but the description looked interesting.
YouTube TV has a highly filterable browse function. I can select "Movies" and I'll see everything currently on, what's available on demand based on my viewing habits, or I can search by genre across all the channels (see image). If I don't want to watch one of these movies on demand (often with forced commercials), I can set a recording and it will automatically record the next airing of that movie even if it's weeks from now. I use YTTV like I do Netflix, Prime or regular Hulu.
For premiums, I either browse that specific channel's on demand library, which includes pretty much anything that would ever air live in the coming weeks. Though I actually prefer to use the premium's separate channel app to browse and watch its content to get 5.1 audio, the only real complaint I have about YouTube TV.
Similarly for non-premiums, I can click on any channel's name in the guide and get a full rundown of everything on demand, live, or coming up.
Bottom line: I don't agree with you that a 14 day guide would be a disadvantage. A short guide may be your preference, but it is certainly not mine.
Once I learned how to take advantage of the many tools YTTV provides to browse and access content, I found it a much more efficient way of finding more than enough to watch. My unlimited DVR library runneth over.
EDIT: BTW, the above image is only showing one row of content for this filtered browse of Movies\Science Fiction. I can similarly do filtered browses of all other manner of content: News, Reality TV, Dramas, Comedy, Family, etc.