Sect itself not only makes sense to me, it's straightforward and easy to determine. What isn't easy, is understanding is how it affects the Chart. Two Charts, say two hours apart, can go from being Night to being Day. This means a drastic reversal in team-native. The Planetary sects (provided the Moon is still in the same Sign) don't change.
So far, we are clear and in agreement.
For example, Saturn in Leo is in-sect by Sign in both cases, but team-native for Day-chart and not for Night-chart.
Ok, so pause here for a moment. What does being on "team native" really mean? It means that we need to suspend what we think we already know about astrology for a moment, and get back to basics. Emitting and receiving. Diurnal planets generally (and I do mean generally) emit, that is, cause things to happen, while nocturnal planets generally recieve things that happen. That is the starting point. Remember back to the elements/quadriplicites, and the natures of the planets themselves.
Saying Saturn in Leo is "in sect by sign" is what got us into this mess in the first place, and you are not alone in the confusion. Sect is easy, as you have pointed out. What isn't easy (I guess, it's easy for me, but I've run into this question so many times that I now understand it isn't easy for everyone) is "similitude." Because some idiot ancients conflated the two, we are now left to try to separate them again.
Sect: diurnal, nocturnal, determined by where the Sun is. Easy.
Similitude: If a planet is in a sign, quadrant, or degree that agrees with its nature or gender. There is also a delineative value for a planet being in the place ruled by a sectmate.
Diurnal or nocturnal, depending on the chart light (day or night) tells us what happens because of the native, that is, because of the choices the native makes. And yes, this means that those born in the night get to make choices too. It's why the calculation for the Lots of Spirit and Fortune are different for day/night births.
So, here's a specific question: When it's a Malefic like Saturn, is it better to have Saturn on team-native or off; and, in the case of one or the other, is it better to have Saturn in-sect by Sign or out-of-sect?
You know the actual answer is going to be "it depends on the chart," right? But in general, you want (anyone wants) Saturn to be the lies you tell, not those told to you. You want Saturn to represent the harm you cause, not the harm that comes to you...get it? But mostly, we want Saturn to be in sect, in a place that he is somehow dignified, and somewhere he can sucessfully bring about his significations while mitigating the damage that is his inherent nature.
Would you rather reject others, or have them reject you? Saturn, when dignified or in sect and bonnified, can bring hard lessons, but the lessons of Chronos stand true. Even the malefics have their uses.
For a Benefic like Jupiter, clearly better on team-native and in-sect by Sign. But does Jupiter STOP being beneficial when it's in a Night-chart (in which event, possibly better to have it out-of-sect by Sign)?
NO. Jupiter is Jupiter is Jupiter. No matter what team they are on, the benefics will always try to produce good things. Having said that, sometimes the "good things" they try to produce are actually going to be pretty bad things overall.
This is so much easier to explain to people who start with understanding the four humors and planetary nature, lol. I fear I've made more of a hash of it than we had to start with.