"The 1 minute melee round assumes much activity - rushes, retreats, feints, parries, checks, and so on. Once during this period each combatant has the opportunity to get a real blow in. Usually this is indicated by initiative, but sometimes other circumstances will prevail." - Player's Handbook, page 105
In the 1st edition Advanced Dungeons & Dragons rules, a round lasted for 1 minute. The explanation above encapsulates many of the rule-making decisions within that show how abstractly the concepts were being used. In actual play, I've never known a gamemaster to use this literal explanation for what is occurring in the round. The 1 minute round was meant to be broken down into 10 six-second segments. Spell-casting during combat was meant to endanger wizards as much as it was to spoil their magic. Consider the following statement:
"Spell-casters will always insist that they are able to use their powers during combat melee. The DM must adjudicate the success of such use. Consider this: The somatic (movement) portions of a spell must be begun and completed without interruption in a clean, smooth motion. The spell as a whole must be continuous and uninterrupted from beginning to end. Once interrupted, for any reason whatsoever, the spell is spoiled and lost (as if used). Spells cannot be cast while violently moving - such as running, dodging a blow, or even walking normally. They are interrupted by a successful hit - be it blow, missile, or appropriate spell (not saved against or saveable against)." - Dungeon Master's Guide, page 65
Such a rule today would be considered harsh and inviolate of the inherent "fun" of playing a wizard. I suspect this rule being contested by players is what led to the Concentration skill in later editions.
Speed factors look to be an important part of 1st edition, where strange advantages present themselves:
"When weapon speed factor is the determinant of which opponent strikes first in a melee round, there is a chance that one opponent will be entitled to multiple attacks. Compare the score of the lower-factored weapon with that of the higher. If the difference is at least twice the factor of the lower, or 5 or more factors in any case, the opponent with the lower factored weapon is entitled to 2 attacks before the opponent with the higher weapon factor is entitled to any attack whatsoever. If the difference is 10 or greater, the opponent with the lower-factored weapon is entitled to 2 attacks before the opponent is allowed to attack, and 1 further attack at the same time the opponent with the higher-speed-factored weapon finally is allowed to attack." - Dungeon Master's Guide, page 66
This implies that a thief using a dagger (speed factor 2) will always get to attack twice against a fighter with any kind of sword (speed factor 5 or more). Is it any surprise that most groups of players never paid attention to speed factors? I remember using speed factors with only one GM (as a negative modifier to initiative), but then he also didn't use the official explanation of 1 round equaling 1 minute of time.
Time keeping isn't essential for determining combat. You don't really need to know how long it takes to wield a battleaxe against a dagger-wielding thief or a pseudopod-swinging otyugh. Time keeping becomes a huge factor once you add magic though, many spells require a full round to cast or are pared down to segments. Just flipping open to a random page in the Player's Handbook one third of the spells require 1 round, another third of the spells take 5 or 6 segments, and the final third require a full turn to cast. And there's the rub!
1 segment = 6 seconds
10 segments = 1 round = 1 minute
10 rounds = 10 minutes = 1 turn
Just as many of the Old School Renaissance rules systems use a 10 second combat round as the ones that use the classic 1 minute round, and almost all of the OSR games keep the use of 10 minute turns. Though most simply instruct the players to track time outside of combat with regular minutes and hours.
Third edition D&D did away with this complexity entirely! A round represented 6 seconds of time, and the 10 minute turn was abolished. Initiative was now much more abstract and rolled with a d20 instead of rigidly timed with the round segments by rolling a d10. Speed factors for weapons disappeared. Casting times for spells were no longer broken up into a strange calculation of time and were simply described as "1 action" or in the cases of complex and powerful magics an actual time of "1 minute" "30 minutes" or "1 hour" was listed.
I appreciate the simplicity.