It depends on what alternatives I have available. Prior to this year, I was aiming for 3-6 months of liquid savings and the rest in my investment accounts.
Now that reasonable interest rates are available, I have changed my priorities. My goal now is 2 months savings in my checking account. This allows me to cover nearly any expense that comes up without the annoyance of transferring money to cover it.
I keep another 1-2 months of expenses in a MMF earning >4% interest and immediately available for withdrawal.
Then I have a decent amount (no particular target) invested in a short-term treasury ETF (TFLO) earning >5% interest, but it takes about a week to sell and transfer funds if I need it.
Altogether, I’m probably keeping 6-12 months readily available, but most of it is earning interest now. I would also likely get 3-6 months severence if I lost my job and could probably cut back on some expenses to stretch things a bit further.
Finally, I used to contribute to a Roth 401k (I’ve since switched to traditional 401k), so I should be able to access those contributions without penalty, if needed. This would only be relevant for someone in the US though.