When I began watching Brentford regularly (late 1950s early 1960s) the team lineup hardly changed from one match to the next unless there was a serious injury. Bit different now with squads of 30 odd players. I'm pretty sure even the England side that won the '66 world cup stayed pretty well together for a while as well.
The game must have been slower back then and the players less fit, meaning that they could eg carry an injury without it being too detrimental to the team's performance. (Remember substitutions didn't come in until the mid-60's and then only 1 per game)
To take a famous example, the Liverpool team which won the 1st Division in 1965/66 only used
14 players over a 42 game season*, with one of those players appearing just once and another only 5 times!
Five players were ever-presents (42), two played 41, two played 40, another 37, one 28 and one 22. This was from an 18 x man 1st team squad.
Full List here
No wonder when Bill Shankly used to give his pre-match Press Conferences on, I think, the Saturday morning, he would step into the room, take a sheet of paper from his pocket and announce:
"Right lads, it's the same team as last year!"
(I should add that for all his good humour and affection for his players, Shankly was notoriously intolerant of injured players. If he heard that a player wasn't fit to appear, he completely blanked him, no excuses, no reasoning - you stayed well out of his way.)
Which also highlights something else which has disappeared from the game: a manager announcing his team well before the kick-off.
* - Btw, although Liverpool went out of the FA Cup in the 3rd Round and didn't enter the League Cup, they got to the Final of the European Cup Winners' Cup that season, which took up another 9 games (plus a Charity Shield game). Pretty much the same dozen players played all those games too.