not sure if this has been mentioned before
on a mono patch:
keep glide at 0
set the envelope to legato in the utility menu.
set the envelope decay/rel short (1s or less for most things. should be very short if looking for 303 style glides from the arp)
sustain can be full or down as low as maybe 20%
assign one of the modulation destinations to glide
now you set your glide time by how much you apply the Env modulator to the above assigned modulation destination
if the envelope sustain is full/high, just a little modulation is probably fine, but if it's low, you'll have to set the modulation amount pretty high.
this can also work well with the arp if you set the gate time to 90% and use at least 50% "spicy", which can get you a few legato notes if you throw the dice a few times. very easy to get 303-style leads