I think it is important for astrologers to learn to read a chart without a birth time--and with little possibility of rectification. Sometimes--notably for people who lived in the past and are no longer living, and where life-event details are scanty-- it is just the best you can do.
For example, I am a genealogy/family history buff. I haven't had a lot of time to do the charts of all of my ancestors for whom I have birth dates and locations, but I hope to get to them this winter. Not only are significant life events hard to find for an ancestor born in the 18th century, beyond church records of birth, baptism, marriage, and death; but it is hard to imagine what ancestors' lives were like in the 19th and 18th centuries (and earlier.) So rectification would be pretty dodgy.
Nevertheless, I have found Moon-Mercury contacts in my maternal ancestors going back 7 generations, even allowing for a + or - 6-degree variance for the moon position (with a noon default chart.) I have found sun-Pluto contacts in both male and female family members for 3 generations.
In such cases, you just have to forget houses and work with planets in aspect, and planets in signs. Robert Hand's books Planets in Youth and Planets in Transit indirectly give just great ways to think about charts without worrying about houses or even signs, because they focus so strongly on aspects. I believe that Uranian astrology functions in a similar way, in focussing even more narrowly on hard aspects.
Another way, where you have a good birth time, to think through the best house system, is to look at the planetary ruler of the house cusps according to different systems. For example, in some systems, someone with the sun in Taurus might have Taurus on the house cusp [and therefore Venus as cusp ruler] whereas in others, Aries might be on the sun's house cusp [and therefore Mars is cusp ruler.] Well, this makes a big difference if you work with so-called "accidental house cusp rulers" or "lords." The principle here is, "The house over which a planet rules serves the purposes of the house in which that planet stands." It does so both by house placements and also by aspects. So people can play around with these house cusp rulers under different house systems to see if there is a change; and if so, which system works best for them.