Vedic astrology reads your entire chart through the rising sign — called the lagna. The lagna establishes which sign occupies each house and which planets become the rulers of which life areas. Change the lagna and you change the structural architecture of the chart — which planets govern what, how every placement functions, what the timing periods are built to produce.
The rising sign changes roughly every two hours on average, though the rate varies by location and sign. A time error that places you near a sign boundary can change your entire chart structure. A time error that leaves you safely mid-sign may change almost nothing in the main chart.
No. If the Ascendant is solidly in the middle of a sign, five minutes probably changes nothing visible in the main birth chart.
A major additional sensitivity is in the divisional charts. Divisional charts are derived charts built to analyze specific life areas — the D9, which becomes especially important in marriage and long-term partnership analysis, the D10 for career, others for health, spirituality, and more. Their Ascendants can shift faster than the natal rising sign. A time that looks essentially identical in the main chart can produce a meaningfully different D9 or D10.
There is no rule that says "five minutes is always fine." You calculate the nearby times and see what actually changes in that specific chart.
Vimshottari dasha is calculated from the Moon's nakshatra and its exact position within that nakshatra. Birth time affects the Moon's calculated degree — and therefore the dasha balance at birth, meaning how much of the first period remained when you were born.
For most charts, a small time error shifts the dasha balance slightly without changing anything major. If the Moon is close enough to a nakshatra boundary, however, the starting dasha lord itself can change. That is a more significant difference.
Then even a small birth time error can shift the first dasha period from one planet to another. Since the dasha sequence determines a major arc of your life's timing, that matters.
This is one of the reasons birth time accuracy is taken seriously in Jyotish — not as an arbitrary requirement, but because the calculation is genuinely sensitive to it in ways that vary by chart.
Yes, with limitations. Some planetary information can still be used without an exact birth time, and the Moon-based dasha sequence may sometimes be approximated if the Moon is nowhere near a nakshatra boundary. What you lose is confidence in house structure, divisional charts, and fine timing — exactly the pieces that make a detailed Vedic analysis specific.
"Around 3pm" gives you a range of possible charts. 3:04pm gives you one specific chart calculation. The first question is therefore not whether four minutes sounds important — it is whether the plausible time range actually changes any of the placements, divisional charts, or timing calculations you need for the question being asked.