It is surely, like so much in astrology, a matter of interpretation
Anecdotal evidence being the most rewarding (or letting us mull ourselves in the choosing) - here is an example
I have Saturn Conjunct Pluto in Libra at 0.99º
A friend has the same at about 9.00º
The common understanding of this is that it is a karmic proofing ground - where suffering will prove the rule early in life
Although an emotive topic (so I may be biased) the parallels are that the friend and I both had family upheavals which affected us both with trauma - but the overt knock-ons from that seem to have been more a test of endurance for my part. It seems I also had more difficulty handling social development than he did, and was consigned to a 'nomadic' life across several pit-stops, all influenced in stress by comparative financial poverty... boo! Saturn has returned and things are changing
The above aspect is also somewhat generational - many of my friends and acquaintances seemed to be experiencing difficult family situations as we grew up, affecting us all differently. In fact to further look at it - my 'same-day twin', a close friend and one with the same tight orb, had an alcoholic mother who killed herself with drink by the time he was 21. He had financial stability which I did not but who suffered the more painful trauma? Whose father was more absent? hmm...
Sorry for the grim content but it's one that sprang to mind which I could compare and contrast. Here is a 'technical' or intuitive rule:
I would say a rule of three is normally good - in an aspect composed of 9º allowance, then 0-3 could be tight, 3-6 moderate, 6-9 loose. However, one can expect to see the factors in play at whatever lassitude, it once again being a matter of intensity... which is difficult to appreciate without a model of how a 'different' intensity of the same factors is expressed / experienced.
Less than 2 or 2.5 degrees is tight, because there are aspects which they depend on such orb. But a tight aspect is as close as it can be. If for example your orb for a trine is 8 degrees, 3 degrees of distance makes that aspect already tight.