Playing High Notes Requires Blowing Edge Angle Changes, Not More Volumes of Air

In response to the poster replying ``It's a wooden bamboo flute brand new.. (sic)'' when the suggestion of leaks/bent keys was proposed in response to the poster's original complaint about inconsistency in sounding out the low notes while in scale with the knowledge that ``high notes have to be blown harder and the lower notes softer'', and the observation that when the poster focuses on just getting the right tone for these notes, it was effortless. The poster's original question was if more practice with breath work was required, stating an experience of about a year:

OP, no offense, but that doesn't mean anything.

If it has keys and associated pads, leakages are possible. Doesn't matter if it is metal, plastic, wood, or bamboo.

If it is a simple flute system with no keys/pads, leakages are still possible, except this time it is your fingers that aren't covering the holes properly. Again, it doesn't matter if it is metal, stone, plastic, wood, or bamboo.

It is only half correct that high notes need to be "blown on harder". You need a higher air speed, but you need it at a shallower angle (relative to directly across the embouchure hole) as compared to the low notes. So blowing "harder" but with the wrong angle does NOT cause the higher frequency harmonics of the standing wave to sound.

Air stream angle of attack on the blowing edge changes as the register of the flute being used changes, with the lower registers have steeper angles compared to the higher registers.

Air steam angles of attack are also affected by how you seat your flute's embouchure hole relative to your embouchure. Assuming that your flute is of a decent playable quality, you will need to find that sweet spot.

If you haven't had lessons with a teacher, you might want to consider having one to more accurately and quickly diagnose and fix any issues that you are facing as they can observe how you are playing. Often times when people are facing trouble in playing and they try to describe it in words, they tend to miss out quite a few very important points, because they aren't aware of what it is to look out for since there are so many minor things that can stack into a major problem. A good teacher can help with the awareness bit and can lead to geometric improvements in playing ability.

You have also asked the correct rhetoric question: everyone can always benefit from more practice, provided they are practicing CORRECTLY.