In such a sentence as 疲れているが、やっぱり行くつもりだ can you substitute やはり with さすが, with the meaning of "as one would expect", "also", "as I thought", "still"? how does the meaning change in this sentence? I can't grasp the real meaning of both adverbs in their daily usage.
1) 'after second thought'. In this usage, the colloquial form やっぱり can be used.
2) 'as expected'