So from Picard season 3, we know the Enterprise E only served 2373 (?) To at best 2386. The F serves 2386 to 2403.

Prodigy is going to likely show us the Voyager-A as of 2385ish, come it's second season. The original being decommissioned after 7 long hard historic years in the DQ.

Now there's an Easter egg on screen in Picard 2403 of the Voyager B! Meaning the A is only in service 2385ish to sometime 2400.

The Titan was 2379-2398 and then torn down and reformatted into the Titan A as of 2402.

Why are late 24th/early 25th century ships so brief for this world?

Yes, the Ent D only made it 7 years. The Defiant less than 5. NX-01 10 years, 5 of them time skipped to the finale. But those were particular exceptions it felt like.

The Excelsior and Miranda class was always presumed to have been in service for DECADES. But now it seems like they just kept building them and throwing them out after 15-20 years? At the maximum?

It just feels wrong.

Feels weird to have so many As and Bs so quickly. Especially since Voyager J is 800 years away.

The Enterprise legacy had the B and C for 2293 to sometime 2330s, and the C was 2330s to her loss in the 2340s? Then a big gap of decades until the D in 2360s.

Weird!

The original Enterprise was 2245-2285 or so. 40 YEARS, multiple refits. And that was implied to be the standard of the day.