How can I make friends faster?

I can’t act on this now anyway but for when I can

I can go to an event & talk to people but then I never see them again.

I want to be the one who asks for a social media swap.

But some people say don’t do this ask them to an event after the event so they can get to know you.

But just the THOUGHT of doing that sounds exhausting.

After say 2-4 hours at a social event I’ve had enough & ready to go home even though I’ve had a good time & I’ve chatted to people.

I’d rather more things but shorter durations.

Than spending a whole day socialising with new people.

I also live in quite a socially reserved city & I spent half my life elsewhere so I didn’t grow up here.

So what should I do?

Suck it up & do the after events?
Ask for the number/social media swap?

I’m not doing neither cos I’m sick of meeting cool people but not actually making friends that I can stay in touch with & also do things socially with another time.

For context, I’m an older female & I’m not in the USA