How to improve at blitz?

I am wondering if its even possible once you reach a certain age to improve at blitz and your rating maybe capped.

Nevertheless, I was never a great blitz player otb and online and had ratings much below my slower time controls both online and otb since I was younger even.

I get caught in between with time management when I should be using my intuition rather than calculating. When I take too long calculating, I get time disadvantage. When I move too quick, I tend to blunder more.

I enjoy playing blitz and most of my games will be playing 5-0. I probably should play 5-3 to not get flagged in winning positions.

I have a decent mouse and despise bullet. I never liked it even when I was young.

I am old enough to remember when 2-12 was the standard online time control with FICS and ICC.

Just wondering if anyone had some advice to get the rating up higher or to confirm that once you hit a certain age that your rating is capped.

Thanks in advance for any advice or words or wisdom.

im worse at blitz than rapid and bullet and much worse than you overall. i guess trying bullet just for training could help even tho you dont like it? if 1min is too much then a custom game like 1/1 or even 2+2 and getting used to that its not your strong suit so not having expectations that you should be straight away as good as in other stuff
maybe trying somewhere between blitz and rapid for custom games too to find sweet spot for training where you are more comfortable at

Play what you enjoy. If 5 is a struggle play 8.
The psychology of being uncomfortable at that time control won't help clarity. If old like me play what is enjoyable. For me family, locals, and mindless computer with no agenda.

wont help with clarity but wouldnt it help with intuition and thats desireable in blitz
we all are different in ways but sometimes doing harder things but not overdoing them can be eventually fun and fruitful

also time management because you are forced to do it but ofc bad habits can come out of it too so has its own risks