England began with a 45-21 defeat by South Africa in Johannesburg, before flying to Liverpool for a 73-8 home win over Fiji and then claiming a 31-24 victory away over Argentina in South America.
"It's been brutal, there's no two ways about it. We've been speaking about it – why would we not all be playing in one country," Earl told British media on Monday.
"So you just don't travel, you go to one nation and have that festival feel. I'm not paid to make those decisions but it has been tough. It's been tough coming at the end of what's been quite a long season anyway for most of us.
"It's been back and forth, coming back to England, seeing your families and then going away again. It has seemed a bit weird but it's just something we're going to have to get used to because I think it's just the beginning."
England are third in the Northern Hemisphere standings in the Nations Championship, level on points with Ireland.
They next face Australia, Japan and New Zealand in November, with all three matches taking place in London.