It depends on three things.
1. Your prior musical knowledge. (music theory helps you hear)
2. Using your instrument as you practice. (gives you musical context)
3. Amount of focused practice. (practice without engaging your brain is not as effective.)

After years I have now got a decent musical ear but I'm still working on a second one. Pa-dum-tsss.
Joking aside, I remember the feeling of having trained for months and [] seeing little result. I still have that feeling fairly often, and on different exercices.

At some point I realized there was sizable result without realizing it, it's just that the end goal is (a) pretty far away and (b) keeps moving even further away because I keep wanting a bit more, a bit better, and a bit faster.

So if you want to check progress, compare with your earlier self, not your goal.

I guess it depends on your definition of a 'Good Ear' - its a journey - I see self improvement of my ear as a lifetimes work tbh - I'm always blown away by musicians with a great ear and it always spurs me on to improve my skills - as I get older I realise that a great ear and great rhythm are (for me) the most important aspects that can enhance my enjoyment, passion and love for music 🎶🔥🤘🏼

I would just try to get easy songs by ear. After you get 50 songs by ear, see if you can get any easy song with cliche chord progressions as they play and only take your time to figure the key. Forget about the exercises here, they will help a bit but nothing like going to the real world and try it for yourself. Also ear training has to do with understanding how music works in general. Even people that cannot read music or ever studied theory knows more or less how things works and can take things by ear instantly just as a matter of experience.

Another good way is knowing to improvise a bit, because improvising will teach a lot about music in general. you will recognize melodic and harmonic pattern faster.

Honestly. I notice random jumps in improvement every 1-6 months of practice.

It’s like this, you practice with little improvement, you have good, days bad days, you notice something new, you notice something very difficult.

With consistency and continuous effort, you might notice a small jump in your abilities if you’re lucky every month or every 3-6 months of effort.

That’s neuroplasticity taking place unfortunately it’s a process, fortunately with continuous effort you get what your looking for. 👍🏾

That's a great shout about improvising - I also agree about the working stuff out by ear - I've been listening to a 4 chord playlist on Spotify with my 10 year old and it's crazy how many songs have only these chords but the endless creativity is amazing and how many big tunes use only I/VI/IV/V - ultimately working towards building confidence to having sessions where we sit at the piano and play them - first working out the resting tone then playing along for fun 🔥