Ideally all games should be played till conclusion. However, in general time limits were slower many years ago -- afterall a higher quality chess game can be expected with slower time limits. For instance when I first started playing competitively in the 1970s, typical time limits were only 40 or 50 moves in 2 hours. Once those moves were played, clock still ran as each player had to make 20 or 25 moves in another hour each.
Players had the right to adjourn when the game was at 5 hours (?) ( as I don't remember) or more WHEN there was another round scheduled after that day.
Then there was an art -- for who should "seal a move". you just did not adjourn the game as is. If you knew that at a certain time, the person on the move must seal, what would you do -- ie; move quicker, so as to put the onus of sealing on the opponent or did you purposely wait longer, so that you would seal ?
Whoever was on the move would write his move down ( unbeknownst what that move was to his opponent ), stop the clocks and write down all pertinent information and seal it in an envelope. Opponent had to agree with the times shown on clock. If he/she sealed an illegal move, they would lose !
My longest game in terms of time was 7 1/2 hours at the Chicago Open. It was the 2nd game played that day. Hours before conclusion, I asked the TD if we could adjourn. He said no -- that he was willing to stay at that playing site for as long as it takes ! Needless to say we both missed a few better moves. My opponent did not make it thru the 3rd time control, as I called time on him.
I was feeling very fatigued and had the better side of a Rook and pawn ending. My opponent, Miomir Stevanovic had smoked thru a pack of cigarettes. It would have been best for both of us, if we adjourned earlier. I do not recall if my opponent continued in the tournament or dropped out.
One of the most famous cases of adjourned games was at the 1962 chess Olympics when the Soviet Union was making the Americans very anxious -- will they put up their World Champion Mikhail Botvinnik against the young Bobby Fischer ? Finally, they made out their lineup card and decided not to give Botvinnik a rest day. Botvinnik sprung an opening innovation on Fischer that he had prepared, but never got to use in his World Title match against Smyslov in an opening variation named after Smyslov ! Fischer refuted it over the board ! The game was adjourned with Fischer better in a Rook and pawn ending. Did Botvinnik spend much time analyzing ? who knows, as he had many "helpers". He was handed analysis the next morning and proceeded to Draw without issue. Is that fair ?
www.chessgames.com/perl/chessgame?gid=1008417&kpage=5
In the past, chess games...including world championship games...were often stopped, sometimes more than once, to resume play at a later time. This gave the players an opportunity to rest up before continuing. So of course chess players would spend hours analyzing the positions with outside assistance, and would even play out the game multiple times with their GM/IM seconds. Of course if we practiced our daily games against anyone other than ourselves, that would be cheating. Now I know that something is hardly considered cheating when the rules are the same for everyone. But still... I don't believe the practice of receiving outside assistance was even frowned on...it was expected. And in games where the results could still go either way, decisive results in resumptions would theoretically come down to whoever had the best help.
I don't think it made too big a difference in the outcomes. But it's still interesting that this practice was allowed.