The creators have stated episodes aren’t necessary in chronological order. Specifically Fall Weather Friends being set before Winter Wrap Up. Assuming May the Best Pet Win is set after Hearth’s Warming Eve and it being Tank’s first Winter works.
 
I agree the age thing is an issue. But assuming multiple years passed between S2 and S5 would only make this worse. I’d go with assuming one year between as avoiding the continuity issue and minimizing the age issue. Why assume otherwise if it makes less sense continuity wise?
 
Sorry for the previous posts. Login issues.

@Incursor  
“Visible lack of aging” is a non-starter, the Cutie Mark Crusaders never showed any signs of aging until there was a multi-decade time skip in the Series Finale despite the fact that one year in the life of a child might see them literally doubling their size. As gets pointed out every time this comes back around, if direct observation is the only metric you’re applying, then Seasons 1 and 2 took nearly three years to play out.
 
Taking all of the seasonally-specific episodes in order of airdate as if they were in calendar order:  
Friendship Is Magic Parts 1&2: Start of Summer, Year 1 After Luna’s Return, starting the new era calendar on the day of the Summer Sun Celebration  
Applebuck Season: Late Summer or early Autumn, Year 1 ALR  
Winter Wrap Up: End of Winter/Start of Spring, Year 1 ALR  
Fall Weather Friends: End of Summer/Start of Autumn, Year 2 ALR  
Luna Eclipsed: Late Autumn, Year 2 ALR (Halloween equivalent)  
Hearth’s Warming Eve: Midwinter, Year 2 ALR (Christmas equivalent)  
Family Appreciation Day and The Super Speedy Cider Squeezy 6000: Late Autumn, Year 3 ALR (Where the Apple Lies establishes that Zap Apple Season happens at around the same time as Cider Season, and Applejack expressly states “Cider sales keep our business afloat through the Winter”, a time skip of at least three calendar seasons)  
Hearts And Hooves Day: Spring, Year 3 ALR (Valentine’s Day equivalent)  
Princess Twilight Sparkle Parts 1&2: Start of Summer and Year 4 ALR  
Bats!: Late Summer or early Autumn, Year 4 ALR (happens during Applebuck Season)  
Tanks For The Memories: End of Autumn/start of Winter, Year 4 ALR  
Hearthbreakers: Midwinter, Year 4 ALR (Christmas equivalent)  
Scare Master: Late Autumn, Year 5 ALR (Halloween equivalent, a time skip of at least three seasons)  
A Hearth’s Warming Tail: Midwinter, Year 5 ALR (Christmas equivalent)  
Where the Apple Lies: Late Autumn, Year 6 ALR (happens during-or-after Cider Season, a time skip of at least three seasons)  
The Break Up Break Down: Spring, Year 6 ALR (Valentine’s Day equivalent, a time skip of at least three seasons)  
The Hearth’s Warming Club: Midwinter, Year 7 ALR (Christmas equivalent, a time skip of at least three seasons)  
Going To Seed: Late Summer or early Autumn, Year 8 ALR (happens during Applebuck Season, a time skip of at least two seasons)  
The Summer Sun Setback: Start of Summer and Year 9 ALR, a time skip of almost a full year in just seven episodes!)  
Best Gift Ever: Midwinter, Year 9 ALR (Christmas equivalent)
 
As you can see, taking them in order still ends up with the series going at least eight and a half years, it just introduces several utterly absurd time skips. Your assertion that “not mentioning an annual event means it didn’t happen” is quantifiably incorrect, since annual events like The Running Of The Leaves, Rainbow Dash’s Birthaversary, and Twilight’s birthday have only been brought up once in the series, meaning everything would have had to happen in less than one year, despite multiple occurences of Nightmare Night, Hearth’s Warming Eve, and the Summer Sun Celebration.

@TexasUberAlles  
The shorter timeline not having Winter in-between would best support the lack of aging viable aging.
 
And since the creators have admitted a consistent time isn’t a priority we are limited to what’s observed in work unless they say otherwise. And since what’s in work only fits there being no winter between that’s what we have to assume unless similar proof is prevented otherwise. That so much happened between seasons seems no more outlandish than the existence of magical ponies.

@Incursor  
There was a lack of any winter episodes between S2 and S5  
Correlation =/= causation; this is a cartoon written by many different people, not a progressive timeline documentary, and all that can be conclusively determined from a lack of Winter episodes in a given time period is “FIM didn’t produce any Winter episodes in this time period”.

@Archonix  
That’s a default assumption, which is what we did. I believe what is stated or shown in-work trumps everything unless proven impossible. Is there any reason to assume more than a year passed here? There was a lack of any winter episodes between S2 and S5.

i dunno much about horse years but i’m guessing the cmc’s would probably be something close to teenagers at least if five years had passed

I remember when bronies were trying to sort the episodes of s1 and s2 into “in universe continuity”
 
It never worked.
 
Pony seasons don’t work that way.

@TexasUberAlles  
I’ve seen more ridiculous.
 
“30 moons/100 moons” anyone?

@Background Pony #DF64  
Exactly– which is to say, ridiculous.

Seems to be roughly in keeping with season 4 premier being one year after series premier.

@Psyga315  
I almost wish that the ponies would say things like “but that happened over 30 moons ago!”

@Archonix  
Floating timeline

You know, it’s probably this bloody argument that annoys me more than anything else in the fandom.
 
Simple television rule: one season = one year. Anything that appears to contradict that is merely a continuity error.

@Ping_chan  
So… Moons, in other words?

Or, the ponies concept of how long a year takes, or the time between seasons, are different than how we would expect.

@Psyga315  
Obviously you can’t take season 4/5 episodes and transplant them in seasons 1-3. But season 1-3 episodes can be reordered fairly freely. Season 4 episodes can happen in almost any order. But season 4 must take place after MMC, and season 5 must take place after Tirek.

@JP  
Yeah. I’d subscribe to that idea where all the episodes are connected somehow, but the problem is explaining Twilight’s disappearing and reappearing wings.

Or May the Best Pet Win! took place in season 3 despite of being a season 2 episode. The episode order isn’t completely fixed.