Your observation is true, and it's a consequence of 1) playing in a strong division, and 2) finishing #1 or #2 in the division, and consequently playing the #1 or #2 teams from the corresponding conferences the next year.
Example. . . last year the Seahawks finished #1 in the NFC West. The scheduling for this year for the NFC West was 1) each team played the other NFC West teams twice, 2) each team in the NFC West would play every team from the NFC North Division (Green Bay, Detroit, Chicago, Minnesota), and 3) each team in the NFC West would play every team from the AFC North (Pittsburgh, Baltimore, Cleveland, & Cincinnati). That gives a total of 14 games.
The final two games would be played by NFC West Teams against teams from the NFC East Division and NFC South Division who finished at the same position in their respective conferences. Therefore, Seattle -- who finished #1 the previous year, played Carolina, who finished #1 in the NFC South, and Dallas, who finished #1 in the NFC East.
Arizona, who finished #2 in the division in 2014, had the same schedule as Seattle, except they played the number 2 team in the NFC South -- New Orleans, and the #2 team in the NFC East -- Philadelphia.
The same was true for the 49ers -- same schedule, except they played the number 3 team in the NFC South -- Atlanta, and the #3 team in the NFC East -- the Giants.
So -- success on the field translates into a harder schedule the next year.