I think it’s safe to say that the house system used affects the timing of events – be it internal or external that relate to the succedent and cadent houses i.e. 2nd, 3rd, 5th, 6th, 8th, 9th, 11th and 12th.
Case in point: I use the equal house system. I have a client Suzie Flowers. Transiting Saturn conjuncts Suzie’s 3rd house in June 2017 using the equal house system. A possible interpretation is that her sibling(s) may be going through a difficult time, a time to be realistic, responsible and disciplined in meeting his/her commitments.
Suzie wrote to me recently saying that her sister is going indeed going through tough times but the timing is off. That doesn’t come as a surprise to me as it’s tough to pinpoint an exact timing unless you do detailed forecasting work – look at full/new Moons, transits of the inner planets, etc. But also, I wonder how would the timing have changed if I had used another house system e.g. Placidus?