According to Don Klipstein :

One that I like but not everywhe Devcon 5-minute gel epoxy. t is a
thickened form that does not run the way the more liquid ones do.
Disadvantage: Some compromise in strength (at least in my experience),
and in my experience takes almost as long as the slow-curing epoxy to
reach its full strength.

5 minute epoxies are generally about 1/3rd as strong as "regular".
Eg: comparing 5min to West Systems "regular" stuff - 5000lb PSI shear
vs. 15,000lb or better PSI shear.

(5min epoxy is generally only about as strong as a good white or
carpenter's glue)

Gels can be nice, but an equivalent can be made by adding silica
powder (a few bucks a pound) to "regular" epoxy. This comes with
a modest sacrifice in strength, but not much.

["Devcon gel" is probably nothing more than ordinary epoxy with
silica or some similar additive.]

We do a fair amount of work with epoxy - glassing, fillets and "part
joining" (model and high power rocketry, where it _has_ to be
as strong as possible and yet light) with wood, cardboard, metal,
fiberglass and other things.

[My son established an altitude record with a rocket that had
hand laid epoxy-carbon fiber and epoxy-fiberglass body tubes, and
fins made with fiberglassed foamcore board, all assembled with
"regular" West. You can't do that with 5 minute or gel epoxy ;-)]

For the most part, we only use 5 minute epoxy for "tacking" (or for
field emergency repairs). Perhaps most often for tacking the edge
of a surface-mount fin to a body tube and getting it aligned. Once
that sets, out comes the West Systems with up to a 3:1 silica:epoxy
mix to fillet the fin roots. That's where most of the strength
comes from.

Even the thicker 5 min epoxies aren't thick enough on their own
for filleting.

We use West for everything _except_ when we need very fast set time,
because West is stronger.

Even then, we can accelerate set time by raising the temperature.

[The West instruction book talks about hot air guns or heat lamps.
Should work with just about any epoxy. Just don't elevate the
temperature past about 160F with ordinary epoxies. It'll destroy it.]
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.