Probably not but there are no guarantees. The January trip may pose problems as it’s so close to the end of the previous one. But, no one can say for sure. You could consider a tourist visa if you’re concerned.
There’s always the chance of problems especially as you are going back so soon. If you do get questioned then the lack of onward travel could give them reason to deny entry. I would cover this in your situation.
Yes so have I. Returned end of May after two months. Will go back for another two months in September.
The issue is the back to back exemptions. I see more cases on these pages of travellers being refused. I’ve even seen it (rarely) where a traveller without a history of border runs was refused. The point is that there’s no guarantee.