There’s no reason why Vikings could not have sailed much further south of Vinland; why stay in the frozen north, when there were undoubtedly warmer lands further on?
Well, Vinland wasn’t the frozen north at that time. That’s why they called it “Wine-land”, because grapes were growing in Northern latitudes during that time.
More than likely they did. A square-rigged ship doesn't tack into the wind very well. Viking long ships and their later, beamy trade vessels were square rigged. Often times you have to change latitudes to pick up prevailing winds going in the opposite general directions. That would entail sailing along the coastline -- perhaps during a change of season -- looking for a consistent shift in the winds.
There's another factor to consider... ship maintenance. Clinker-built hulls have a shit-ton of iron nails holding them together to create those graceful curves. That's a lot of stress and as a ship hogs (flexes) in the waves a lot of nails are going to pop & be lost. The Vikings would need to put their ships up on a sandy beach and go looking for bog iron. Improvise a hearth to 'cook' the iron-bearing rock, then hammer out new nails. Very time consuming and labor intensive. Archeologists are using satellite technology and they think they've found one down the coastline at Point Rosse.
So you have to think in terms of what would be required to sail back & forth and other limiting factors that the Norse would need to take into account.
You have to remember what Europe was like a thousand years ago.
Most of the masses were illiterate, and information was a very valuable and well guarded commodity.
If you discover new routes to new lands, you didn’t climb up and shout it from the mountain top and proclaim yourself heroic. You kept it to the vest like you were holding aces.
Whether it be the vatican, clandestine societies, or even lords/monarchs/dynasties, you wanted to make sure that others were not going to get a jump on your new worlds. Information in general was well kept, and hard to disseminate even if you wanted to. If you had charts and maps that others didn’t, you probably felt like you were on top of the world. Pun intended. Even crusades to the holy land were treated like a competitive race for glory. You’re status in nobility could be vaunted with new discoveries so you didn’t give away trade secrets.
/bingo