I want to preface by saying that this sounds, and looks, very well done. Though, there are some areas of repetition, it's not too much and is pleasing to a listeners ear. The differences in mode without actually changing the mode, in some areas is also very cleverly done! Overall, the sound of it is pretty great, my friend!
However (I know, I'm sorry. lol), In my personal opinion... Percussion parts being written in, such as Timpani, Sus. Cymb., Concert Bass, and/or Grand Staff Marimba, I think, could benefit the piece greatly. I kept hearing bits of percussion parts in my head that would've added much more emphasis on some of the phrasing you have here, and would've overall given it a more grandiose sound, all together.
One thing I've noticed... (There's more than one phrase within the composition that does this, but this example is just the one that I see, most conveniently at the time of typing this) on page 27 of the score, in measure 197, for Violins 1 & 2, and Viola, the rhythm notation is incorrect for these passages. If you start a measure in 4/4 with an eighth note, it's typically seen as improper to immediately follow that eighth note with a quarter note. You're essentially notating a quarter note, starting on the up-beat of beat 1, and this is confusing to players, and to anyone reading along, since a quarter note will always start on a down beat, in any given score ๐
.. Instead, replace each quarter note with 2 eighth notes tied together. It helps the player to subdivide the syncopation that you have, there.
Secondly, a piece this long, really should have Rehearsal marks for when/if an ensemble may pick this piece up to perform at some point. Otherwise, the conductor and players will all have to look at each page, or, count bars to find a specific place in the music to go back and practice through. I usually break rehearsal marks up into sections/sub-sections. (When transitioning to a new phrase/variation of the motif, would be section A-Z, and subsections would be A1-10 - Z1-10 to mark areas of note that involve any variation OF the variation sections, if you understand what I mean by that. Take a look at my piece, here, for reference. Look for A, A1, A2 etc.. You'll see what I mean lol)The Long, Arctic Midnight.pdf
Lastly, I observed that the Oboe and Horn parts have a lot of areas where a player may strain themselves early on in the piece, resulting in fatigued embouchure muscles before the piece has ended. This would make for a higher chance of players making a mistake in intonation, or even playing higher pitches with any sort of power or emphasis, nearing the end of the performance. There was also a moment there, in the first section of the piece, within the repeat bars, where the Horn has a very long set of tied whole notes. Players have to breathe! (Unless they learned how to circular breathe, but in my experience, as a trumpeter, most people aren't too privy to having any desire to learn that skill, so not a lot of wind instrument players can do that.)
To conclude, the symphony you've written here has a very traditional sound to it, the writing is complex and for the most part, done really well. Honestly, the type of music written here isn't something that I'd ever pull off with any effectiveness... lol but Take what I say with a grain of salt... I'm also someone who's been out of the music game for a long time, and only within the last 6 months have I picked things up again. I'm not even back where I "left off" at. I dropped out of college pursuing a bachelors in Music Theory & Trumpet Performance, after the 1st year, and became a mechanic shortly after. So I'm still kicking the rust off my brain for my music theory knowledge. And have also never been "instructed" in composition methods, and I'm more of an autodidact who can read music well, and who likes to poke around on a score sometimes. Someone else here, with a high probability, would be able to give you even more to consider, than I will, certainly. Anyway. I like what you've done here, and just take my words into consideration at your own convenience. ๐
Goojahb. ๐