This guide is not something that you should follow...ever.
Let me explain why:
First of all this guide is clearly written for low ELOs. This is evident by the lack of discussion of team fighting strategies and the number of kills cited.
Second of all the explanation of skill use is poor and not helpful. The suggested order of skill leveling is not logical. It is usually very helpful to get ambush level 1 for scouting out the location of the enemy team at the super-creeps. Though i doubt super-creep killing at level 1 happens that often at begginer elos.
Thirdly the item build is very poor. The amount of attack speed items here will increase your attack speed in late game team battles with spray and pray from 2.5 to 2.5. At high elos twitches usually build avarice blades --> infinity with furor runes for crit damage. Sometimes frozen mallets are seen as well for the slow. Twitch has great attack speed from his abilties, so increasing the attack speed even more is not an efficent use of gold.
Fourthly the summoner skills are not what would generally be used by a good twitch player. Cleanse is very good on twitch, as it is on most everything else. Often twitches get rally since this is very helpful in achieving an early kill with red rune.
Fifthly, it should be mentioned that getting red rune immediately on twitch at level 1 with ambush, cleanse and rally can get a first blood even against high rated players. Cleanse is better than exhaust since other good players will have cleanse, and you might need cleanse to remove an exhaust or other cc if they have it. Rally because it amps up your damage.
Sixthly, it is often a good idea to have twitch go for this first blood attempt on the middle lane, which if successful or almost successful will allow him to dominate the middle lane unless the enemy team brings multiple people in.
Seventhly in mid game ganking often your original lane is warded, and good players will not come to your lane to gank themselves. Having someone else cover your original lane while you harass the other lanes/ help bring down towers is a better strategy then remaining in your starting lane.
You are right however that late game battles with twitch are all about timing and positioning. I also agree that twitch is great for solo queuing since he can take advantage of poor play on your enemy's parts. All in all your guide is well written but your opinions on twitch strategy clash greatly with mine, and I think you should seriously consider revising your item build to include crit, crit damage, and damage rather than attack speed.
P.S. non of the twitch builds on this forum are something that you should follow, SmeecsRaege (I think I misspelled that) had a good guide that was rendered obsolete by changes to Twitch's ultimate.