DCF EBITDA Exit Multiple vs Implied LTM EV/EBITDA Multiple

I'm doing a dcf and I was wonderind what the differences should be between the EBITDA exit multiple you use to find your terminal value and the implied LTM EV/EBITDA multiple you get as a result of calculating enterprise value. My implied LTM EV/EBITDA is almost double what I get from using the exit multiple to get to terminal value. My question is, when doing a DCF should you be running comps to find the ebitda exit multiple or should you be targeting a certain LTM EV/EBITDA multiple (which would essentially be a proxy for the sale)? For example, if I spread comps and get an EV/EBITDA multiple of 15x and use this 15x as my EBITDA Exit Multiple does it matter if my implied LTM EV/EBITDA multiple is 30x? Wouldn't this LTM EV/EBITDA multiple be too high compared to what the comps suggest?