How to find total effects of current Vimsottari Dasa

How to judge whether a planet is benefic or malefic during its vimsottari dasa?

If it is significator of 3rd house, it will make the person more courageous, creative and will help him/her to write and publish but at the same time it will cause him/her seperation from mother.
This is because 3rd house is 12th with respect to 4th house.
If a person gains money through 2nd house significator/lord, it will cause ill health to his spouse as 2nd is 8th with respect to 7th house.
So, if we look that way, no planet is totally benefic or totally malefic.
vimsottari dasa of 9 planets

Then how to judge if a planet will give good or bad results during its vimsottari dasa?

There are two methods to verify the overall impact of a planet’s mahadasa(period_ and also variations in results offered in different bhuktis(subperiods).

First Method :
When a particular planet’s mahadasa starts, note down the course of events that happen during first bhukti of that planet.
For example if you are running Venus Mahadasa which lasts for 20 years, check out what happens during Venus-venus bhukti which lasts for 40 months.
Now further divide these 40 months in same ratio as all antardasas of venus are divided.
Checkout and note the events that occur during these 40 months and for example if most favourable antardasa is of mercury which lasts for 170 days, the you can conclude that venus-mercury bhukti which will come after 16 years of venus mahadasa and lasts for 34 months will be the most favourable one for you.
If Venus-venus-saturn antardasa which lasts for 190 days is bad for you, then you can conclude that venus-saturn bhukti which comes after almost 13 years of venus mahadasa and lasts for 38 months will be most unfavourable.

So we can conclude that in venus mahadasa, saturn is most malefic and mercury is most malefic based on above observations.
These malefics and benefics are limited to this dasa only.
In other mahadasas of other planets, they may change, which has to be observed at the begining of those dasas.

Second Method :

Taking the above example of running venus dasa, if you have already crossed venus-venus bhukti and do not remember much about the course of events that occured at that time, then use this method to find what will happen in remaining bhuktis of venus mahadasa.

Checkout from ephemeris on what date does moon transit though a constellation owned by venus.
Venus own 3 constellations(nakshatras) : Bharani (in aries), Poorvaphalguni (in leo) and Poorvashada (in sagittarius).
Moon transits on of these constellations for almost 24 hours.
For example if moon transits poorvaphalguni constellation for 23 hours and 3 minutes, then divide this 1383 minutes in same ratio as you divide bhuktis of all planets in venus mahadasa.
venus-venus bhukti will be 1383×20/120 = 230 minutes 30 seconds on that day.
venus-sun bhukti will be 1383×6/120 = 69 minutes and 9 seconds on that day.
similarly find for how much time each bhukti lasts when moon transits a constellation owned by venus.
Not down the events on that day and if good events happen during some bhuktis then those planet’s bhuktis will also be favourable during venus mahadasa.
Similarly you can find out for future bhuktis too if you are middle of venus mahadasa.

However, this method is useful only to find results of currently running mahadasa.
For future mahadasas, you need to check results on moon’s transit on constellation owned by that planet only when that mahadasa starts.
You cannot verify Sun mahadasa results when you are running venus dasa, even if you note moon’s transition effects on krittika, uttara, uttarashada constellations.