I think that what is written needs to be honored first, because a lot of times the bass has a specific harmonic role (sometimes not starting with the root on 1) or playing lines/hits with the players in and out of the various horn/sections sections. Doubling with the bari sax or bass trombone happens frequently. A lot of charts have rhythm section specifics that need to be played as written. Numerous key changes with the chart happen all the time. That brings up the need to be skilled at reading and "playing" the rests as well as the notes.
As mentioned by others, measures marked with only chords are open, but with the caveat that it should match the feel and momentum of the tune arrangement.
After you do that, you can make the attempt to change it from the original, but the appropriate caution needs to be taken not to upset the arrangement for the other players and the audience.
Part of my background is in playing in full big bands, some with singers, with extensive libraries. Double bass to electric fretless bass guitar. Everything from early dance music to Kenton, Wolpe, Ellington, Newsom, Goodwin, etc..
The libraries literally are numbered past 500. In one 2x/month band (this morning!), it is a sight reading adventure. Some tunes I've seen before in other bands; most, at least for me, are a cold read.
In situations where I've subbed for bassists in another bands, I usually "read the ink" by default. By the way, I've come across charts with no written chord changes in most of the chart.
I'm not a great reader, but playing in situations where things parts are written like big band, musicals, orchestra, encourages one to get better at it.

I continue to work on this.
Learning your instrument in terms of navigating your way around the whole length of the neck will go a long way in making the reading chart experience less stressful. Hence, I agree the prior posts' very valid reference to employing Simandl or other methods, even on electric bass guitar. If you can take the charts home, practice by working out optimal or alternate shifts with the as important goal of NOT looking at the neck as much as possible. While I'm not suggesting that you memorize the pieces, this practice facilitates using the alternate neck positions on-the-fly. Memorization doesn't work for me in these situations, because it could be months/years before I ever have to play the chart again.
Learning to read ahead as you go is another helpful skill.
Using a pencil, to make notes on charts is also acceptable. However, if your subbing, check with the bandleader.
If time permits, review the chart map BEFORE the downbeat, i.e. what sections are repeated, where the D.S.s and Codas are located, etc.; crucial when sight reading.
All this being said that are those arrangers/copyists that piss you off. For instance a chord from Eb To Edim indicated with the notation showing Eb to Fb!! Not nice when reading at bpm @ 180+.