I think the issue with setting the BTC/kB fee and using the slider, is that if you get the slider in the wrong place you could potentially end up using a sat/byte fee that is 1/10 of what it should be!
Personally, I think that if you are not just going to "use Dynamic Fees" (and people really should 99% of the time), then calculating the actual fee to be used and just entering that directly into the "manual fee" box, is probably safer than using the somewhat confusing "max static fee" in the preferences that is in BTC/kB and the slider... especially because all the recommended fees (from bitcoinfees.21.co and btc.com) are all shown as sats/byte... not BTC/kB.
But, hey... that's just me... find what works for you and go with it